揭建胜

教授,博士生导师,优青

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  • 102019
    吴晓峰同学的论文''Air Effect on the Ideality of p-Type Organic Field-Effect Transistors: A Double-Edged Sword''发表在Adv. Funct. Mater.上

    Abstract


    Organic field-effect transistors (OFETs) often deviate from ideal behaviors in air, which masks their intrinsic properties and thus significantly impedes their practical applications. A key issue of how the presence of air affects the ideality of OFETs has not yet been fully understood. It is revealed that air atmosphere may exert a double-edged sword effect on the active semiconductor layer when determining the ideality of OFETs fabricated from p-type crystalline organic semiconductors. Upon exposing the as fabricated device to air, water and oxygen mainly function as efficient p-type dopants for the active layer in the contact regions, enhancing charge carrier injection and consequently improving device ideality. Nevertheless, as the exposure time increases, the trapping centers for the injected minority charge carriers appear in the channel region, leading to degradation of device ideality. Inspired by the double-edged sword behavior of air, a near-ideal OFET is achieved by ingeniously utilizing the doping/positive effect and eliminating the trapping/negative effect. The effect of air on the ideality of p-type OFETs is clarified, which not only illuminates some common observations of OFETs in air but also offers useful guidance for the construction of high-performance ideal OFETs.


  • 102019
    邓巍老师和陆蓓同学的论文''Precise Positioning of Organic Semiconductor Single Crystals with Two-Component Aligned Structure through 3D Wettability-Induced Sequential Assembly''以封面形式发表在ACS Appl. Mater. Interfaces上

    Abstract

    Highly ordered organic semiconductor single-crystal (OSSC) arrays are ideal building blocks for functional organic devices. However, most of the current methods are only applicable to fabricate OSSC arrays of a single component, which significantly hinders the application of OSSC arrays in integrated organic circuits. Here, we present a universal approach, termed three-dimensional (3D) wettability-induced sequential assembly that can programmatically and progressively manipulate the crystallization locations of different organic semiconductors at the same spatial position using a 3D microchannel template, for the fabrication of the two-component OSSC arrays. As an example, we successfully prepared two-component, bilayer structured OSSC arrays consisting of n-type N,N′-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide and p-type 6,13-bis(triisopropylsilylethynyl)pentacene microbelts. The bicomponent OSSCs show ambipolar carrier transport properties with hole and electron mobilities of 0.342 and 0.526 cm2 V–1 s–1, respectively. Construction of complementary inverters is further demonstrated based on the two-component OSSCs. The capability of integration of multicomponent OSSC arrays opens up unique opportunities for future high-performance organic complementary circuits.


    封面原文点击此处




  • 092019
    贾若飞同学的论文"Unraveling the Mechanism of the Persistent Photoconductivity in Organic Phototransistors"发表在Adv.Funct.Mater.上

    Abstract

    Persistent photoconductivity (PPC) in organic phototransistors provides an opportunity and broad prospects to achieve many emerging applications in optoelectronic devices. However, a fundamental understanding of the PPC behavior is still a key challenge impeding its practical applications. In this study, we present, for the first time, a mechanism of electron trapping in oxygen-induced deep levels in organic semiconductors for the clarification of PPC behavior with solid evidence. Both theoretical simulation and experimental investigation unveil that oxygen in air atmosphere plays a decisive role in determining the PPC behavior. Oxygen molecules can induce deep defect levels in the energy bandgap of organic semiconductors, which will act as deep traps for photo-generated electrons. The trapped electrons will be maintained in the traps and undergo a very slow releasing process after light illumination, thus leading to a noticeable PPC behavior for the organic phototransistors. The proposed mechanism shows good universality and can be applicable to a host of organic semiconductors for explaining the PPC behaviors. Our work reveals the significant role of oxygen in PPC behavior and also provides guidelines for controlling the unique PPC behavior toward device applications.



  • 092019
    王金文同学的论文"External-force-driven solution epitaxy of large-area 2D organic single crystals for high-performance field-effect transistors"发表在Nano Res.上

    Abstract

    Growth of two-dimensional (2D) organic single crystals (2DOSCs) on water surface has attracted increasing attention, because it can serve as a molecularly flat and defect-free substrate. However, large-area growth of 2DOSCs with controllable crystal orientation on water surface remains a key challenge. Herein, we develop a simple method, i.e. external-force-driven solution epitaxy (EFDSE), for the large-area growth of 2DOSCs at air/water interface. Using 2,7-didecylbenzothienobenzothiophene (C10-BTBT) as an example, high-quality 2D C10-BTBT crystals on centimeter scale are generated by directionally controlling the spreading of organic solution on water surface with external force. Benefiting from the controllable crystal orientation with optimal charge transport, the corresponding 2DOSC-based organic field-effect transistors (OFETs) exhibit a high carrier mobility of 13.5 cm2·V−1·s−1 (effective mobility ≈ 5.4 cm2·V−1·s−1 according to a reliability factor of 40%), which represents the best result achieved for water-surface-assembled 2DOSC-based OFETs. Furthermore, by transferring the C10-BTBT 2DOSCs to flexible substrates, devices with excellent bending stability are achieved. It is anticipated that our method will provide new insight into the controllable growth of large-area 2DOSCs for high-performance organic devices.



  • 082019
    邓巍老师的论文"Two-dimensional Ruddlesden-Popper Perovskite Nanoplates Based Deep-blue Light-emitting Diodes for Light Communication"发表在Adv.Funct.Mater.上


    Abstract

    Ruddlesden–Popper perovskite, (PEA)2PbBr4 (PEA = C8H9NH3), is a steady and inexpensive material with a broad bandgap and a narrow‐band emission. These features make it a potential candidate for deep‐blue light‐emitting diodes (LEDs). However, due to the weak exciton binding energy, LEDs based on the perovskite thin films usually possess a very low external quantum efficiency (EQE) of <0.03%. Here, for the first time, the construction of high‐performance deep‐blue LEDs based on 2D (PEA)2PbBr4 nanoplates (NPs) is demonstrated. The as‐fabricated (PEA)2PbBr4 NPs film shows a deep‐blue emission at 410 nm with excellent stability under ambient conditions. Impressively, LEDs based on the (PEA)2PbBr4 NPs film deliver a bright deep‐blue emission with a maximum luminance of 147.6 cd m−2 and a high EQE up to 0.31%, which represents the most efficient and brightest perovskite LEDs operating at deep‐blue wavelengths. Furthermore, the LEDs retain over 80% of their efficiencies for over 1350 min under ≈60% relative humidity. The steady and bright deep‐blue LEDs can be used as an excitation light source to realize white light emission, which shows the potential for light communication. The work provides scope for developing perovskite into efficient and deep‐blue LEDs for low‐cost light source and light communication.


  • 072019
    我组工作《基于钙钛矿纳米颗粒/有机半导体单晶复合结构的双波段光电晶体管》被公众号X-MOL咨询报道

    有机-无机杂化钙钛矿是一种性能优异的新型光电材料,它在可见光段具有很高的光吸收系数,且载流子扩散长度和寿命长,已被广泛应用于光伏、发光等器件领域。那么,是否可以将有机-无机杂化钙钛矿材料与有机单晶半导体材料结合在一起,拓宽它们各自的光谱响应范围呢?近日,苏州大学揭建胜团队成功制备了钙钛矿纳米颗粒/有机半导体单晶阵列复合结构,并实现了其在双波段光电晶体管和安全通信中的应用

    详情见原文(点击此处)

  • 072019
    我组工作《聚合物绝缘层上有机半导体单晶阵列的生长及其在柔性场效应晶体管中的应用》在公众号研之成理上被报道

    苏州大学功能纳米与软物质研究院张晓宏、揭建胜教授团队发展了一种在聚合物绝缘层上有序阵列化组装有机半导体单晶材料的普适性策略——极性表面限域结晶法,制备出了具有单一结晶取向的有机单晶阵列,并将其应用于柔性场效应晶体管。

    详情见原文(点击此处)


  • 072019
    热烈祝贺2019届硕士、博士顺利毕业!

    徐秀真同学、张咪同学、赵万芹同学、詹扬扬同学、王伟同学、方欢同学全体顺利通过毕业答辩,携丰硕的科研成果圆满完成学业。祝贺徐秀真同学获得博士学位,张咪同学、赵万芹同学、詹扬扬同学、王伟同学、方欢同学获得硕士学位。

    愿各位毕业生前程似锦!常回家看看!





  • 062019
    姜天昊同学的论文"High-performance Nano-floating Gate Memory Based on Lead Halide Perovskite Nanocrystals"发表在ACS Appl. Mater. Interfaces上

    Abstract

    Lead halide perovskites have been extensively investigated in a host of optoelectronic devices, such as solar cells, light-emitting diodes, and photodetectors. The halogen vacancy defects arising from halogen-poor growth environment are normally regarded as an unfavorable factor to restrict the device performance. Here, for the first time, we demonstrate the utilization of the vacancy defects in lead halide perovskite nanostructures for achieving high-performance nano-floating gate memories (NFGMs). CH3NH3PbBr3 nanocrystals (NCs) were uniformly decorated on CdS nanoribbon (NR) surface via a facile dip-coating process, forming a CdS NR-CH3NH3PbBr3 NCs core-shell structure. Significantly, owing to the existence of sufficient carrier trapping states in CH3NH3PbBr3 NCs, the hybrid device possessed an ultra-large memory window up to 77.4 V, a long retention time of 12 000 s, a high current ON/OFF ratio of 7×107, and a long-term air stability for 50 days. Memory window of the device is among the highest for the low-dimensional nanostructure-based NFGMs. Also, this strategy shows good universality and can be extended to other perovskite nanostructures for the construction of high-performance NFGMs. This work paves the way toward the fabrication of new-generation, high-capacity nonvolatile memories using lead halide perovskite nanostructures.


  • 062019
    张咪同学的论文"Tuning Electrical and Raman Scattering Properties of Cadmium Sulfide Nanoribbons via Surface Charge Transfer Doping"发表在J.Phys.Chem.C上


    Abstract

    Surface charge transfer doping (SCTD) has emerged as an efficient approach to tune the electrical and optical properties of semiconductor nanostructures. As an important II-VI semiconductor, cadmium sulfide (CdS) nanostructures possess superior optoelectronic properties. However, SCTD on the CdS nanostructures remains a challenge, and the underlying mechanism for optical property modulation is unclear. Herein, we demonstrate that both the electrical and Raman scattering properties of CdS nanoribbons (NRs) can be tuned by using MoO3 and benzyl viologen (BV) as surface dopants. The MoO3 (or BV) molecules, which have high work function (or strong reducing capability), can extract (or inject) electrons from (or into) the CdS NRs because of the large difference in energy levels, leading to the electron depletion (or accumulation) within the CdS NRs. By controlling the amount of surface dopants, the electron concentration as well as resistivity of the CdS NRs can be readily modulated. Significantly, Raman scattering properties of the CdS NRs can be fine-tuned due to strong electron-phonon coupling effect. A mechanism based on the semi-classical longitudinal-optical-phonon-plasmon theory is first proposed to explain the SCTD-induced Raman scattering modulation. Our findings offer a feasible route for modulation of electrical and optical properties of compound semiconductor nanostructures.




  • 052019
    赵万芹同学的论文"A Facile Method for the Growth of Organic Semiconductor Single Crystal Arrays on Polymer Dielectric Toward Flexible Field-Effect Transistors"发表在Adv. Funct. Mater.上

    Abstract

    Polymer dielectrics with intrinsic mechanical flexibility are considered as a key component for flexible organic field-effect transistors (OFETs). However, it remains a challenge to fabricate highly aligned organic semiconductor single crystal (OSSC) arrays on the polymer dielectrics. Herein, we propose for the first time a facile and universal strategy, polar surface-confined crystallization (PSCC), to grow highly aligned OSSC arrays on poly(4-vinylphenol) (PVP) dielectric layer. The surface polarity of PVP is altered periodically with oxygen-plasma treatment, enabling the preferential nucleation of organic crystals on the strong-polarity regions. Moreover, a geometrical confinement effect of the patterned regions can also prevent multiple nucleation and misaligned molecular packing, enabling the highly aligned growth of OSSC arrays with uniform morphology and unitary crystallographic orientation. Using 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) as an example, highly aligned C8-BTBT single crystal arrays with uniform molecular packing and crystal orientation are successfully fabricated on the PVP layer, which can guarantee their uniform electrical properties. OFETs made from the C8-BTBT single crystal arrays on flexible substrate exhibit a mobility as high as 2.25 cm2 V-1 s-1, which has surpassed the C8-BTBT polycrystalline film-based flexible devices. This work paves the way toward the fabrication of highly aligned OSSCs on polymer dielectrics for high-performance, flexible organic devices.

  • 052019
    徐秀真同学、邓巍老师的论文"Dual-Band, High-Performance Phototransistors from Hybrid Perovskite and Organic Crystal Array for Secure Communication Applications"发表在ACS Nano上

    Abstract

    High-performance phototransistors made from organic semiconductor single crystals (OSSCs) have attracted much attention due to the high responsivity and solution-processing capability of OSSCs. However, OSSC-based phototransistors capable of dual-band spectral response remain a difficult challenge to achieve because organic semiconductors usually possess only narrow single-band absorption. Here, we report the fabrication of high-performance, dual-band phototransistors from a hybrid structure of a 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) single-crystal array coated with CH3NH3PbI3 nanoparticles (NPs) synthesized by a simple, one-step solution method. In contrast to C8-BTBT and CH3NH3PbI3 NPs with respective absorption in the ultraviolet (UV) and visible (vis) region, their hybrid structure shows broad absorption covering the entire UV–vis range. The hybrid-based phototransistors exhibit an ultrahigh responsivity of >1.72 × 104 A/W in the 252–780 nm region, which represents the best performance for solution-processing, broadband photodetectors. Moreover, integrated phototransistor circuitries from the hybrid CH3NH3PbI3 NPs/C8-BTBT single-crystal array show applications for high-security communication.




  • 042019
    张秀娟老师应邀撰写的综述论文"Precise Patterning of Organic Semiconductor Crystals for Integrated Device Applications"发表在Small上

    Abstract

    Development of high-performance organic electronic and optoelectronic devices relies on high-quality semiconducting crystals that have outstanding charge transport properties and long exciton diffusion length and lifetime. To achieve integrated device applications, it is prerequisite to precisely locate the organic semiconductor crystals (OSCCs) to form a specifically patterned structure. Well-patterned OSCCs can not only reduce leakage current and cross-talk between neighboring devices, but also facilely integrate with other device elements and their corresponding interconnects. In this review, we summary general strategies for the patterning of OSCCs and discuss the advantages and limitations of different patterning methods. Discussion is focused on an advanced strategy for the high-resolution and wafer-scale patterning of OSCC by surface microstructure-assisted patterning method. Furthermore, we highlight the recent progress on OSCC pattern-based integrated circuities. Finally, the research challenges and directions of this young field are also presented.


  • 032019
    我组受邀在Journal of Materials Chemistry C上撰写的钙钛矿量子点LEDs的综述文章2018年阅读量进入前5%排行榜
  • 022019
    邵智斌老师、姜天昊同学的论文"Memory phototransistors based on exponentialassociation photoelectric conversion law"发表在Nat. Commun.上

    Abstract

    Ultraweak light detectors have wide-ranging important applications such as astronomical observation, remote sensing, laser ranging, and night vision. Current commercial ultraweak light detectors are commonly based on a photomultiplier tube or an avalanche photodiode, and they are incompatible with microelectronic devices for digital imaging applications, because of their high operating voltage and bulky size. Herein, we develop a memory phototransistor for ultraweak light detection, by exploiting the charge-storage accumulative effect in CdS nanoribbon. The memory phototransistors break the power law of traditional photodetectors and follow a time-dependent exponential-association photoelectric conversion law. Significantly, the memory phototransistors exhibit ultrahigh responsivity of 3.8 × 109AW−1 and detectivity of 7.7 × 1022 Jones. As a result, the memory phototransistors are able to detect ultraweak light of 6 nW cm−2 with an extremely high sensitivity of 4 × 107. The proposed memory phototransistors offer a design concept for ultraweak light sensing devices.



  • 072018
    邓巍老师的论文"Channel-restricted Meniscus Self-assembly for Uniformly Aligned Growth of Single-Crystal Arrays of Organic Semiconductors"发表在Mater.Today.上

    Abstract 


    Organic semiconductor single-crystal (OSSC)-based field-effect transistors (FETs) with high mobility and small device-to-device variation enable OSSCs to be adapted for practical applications. Research attention has recently been focused on developing simple ways of fabricating large-area OSSC arrays by means of solution-coating techniques. However, the lack of control of the meniscus front, where the nucleation and growth of organic crystals occur, leads to inconsistent crystal alignment and consequently induces large variation in device performance. Here, we propose a universal strategy,termed the channel-restricted meniscus self-assembly (CRMS) method to fabricate ultrahigh-mobility,uniform OSSC arrays. The microscale photoresist channels used in this method produce a confinement effect to reduce the size of the meniscus, enabling the homogeneous nucleation of OSSCs at the meniscus front. Meanwhile, the dip-coating process ensures consistent molecular packing in the OSSCs and thus guarantees their highly uniform electrical properties. Using 2,6-diphenylanthracene as an example, wafer-scale (>2 inch) OSSC arrays with very small size variations (10%) are successfully prepared, which is very difficult to achieve by using the previously reported methods. As a result, fieldeffect transistors (FETs) based on the OSSC arrays show a high average hole mobility of up to 30.3 cm2 V-1 s-1 with good uniformity among devices. This method is general for the growth of various OSSC arrays, facilitating the applications of OSSCs in large-area, high-performance organic electronic devices.


  • 062018
    肖鹏同学的论文"Solution-processed three-dimensional RGO-MoS₂/pyramid Si heterojunction for ultrahigh-detectivity and ultra-broadband photodetection"发表在Adv. Mater.上

    Abstract
    Molybdenum disulfide (MoS2), a typical two-dimensional metal dichalcogenides (2DMDs), has exhibited tremendous potential in optoelectronic device applications, especially in the photodetection. However, due to the weak light absorption of planar mono-/multilayers, limited cutoff wavelength edge, and lack of high-quality junction, most reported MoS2-based photodetectors show undesirable performance. Here, a structurized three-dimensional (3D) heterojunction of RGO-MoS2/pyramid Si was demonstrated, for the first time, via a simple solution-processed method. Owing to improved light absorption by pyramid structure, narrowed bandgap of MoS2 by imperfect crystallinity, and enhanced charge separation/transportation by inserted RGO, the assembled photodetector exhibited excellent performance in terms of large responsivity of 21.8 A W-1, extremely high detectivity up to 3.8 × 1015 Jones (Jones = cm Hz1/2 W-1) and ultra-broad spectrum response ranging from 350 nm (ultraviolet) to 4.3 μm (mid-wave infrared). These device parameters represent best results for MoS2-based self-driven photodetectors, and the detectivity value sets a new record for 2DMD-based photodetectors reported thus far. Prospectively, the design of novel 3D heterojunction could be extended to other 2DMDs, opening up the opportunities for a host of high-performance optoelectronic devices.

  • 052018
    张秀娟老师的论文"Precise Patterning of Laterally Stacked Organic Microbelt Heterojunction Arrays by Surface-energy Controlled Stepwise Crystallization for Ambipolar Organic Field-effect Transistors"发表在Adv. Mater.上

    Abstract
    Ambipolar organic field-effect transistors (OFETs) combining singlecrystalline p- and n-type organic micro/nanocrystals have demonstrated superior performance to their amorphous or polycrystalline thin-film counterparts. However, large-area alignment and precise patterning of organic micro/nanocrystals for ambipolar OFETs remain challenges. Here, a surface-energy-controlled stepwise crystallization (SECSC) method is reported for large-scale, aligned, and precise patterning of single-crystalline laterally stacked p–n heterojunction microbelt (MB) arrays. In this method, the p- and n-type organic crystals are precipitated via a stepwise process: first, the lateral sides of prepatterned photoresist stripes provide high-surfaceenergy sites to guide the aligned growth of p-type organic crystals. Next, the formed p-type crystals serve as new high-surface-energy positions to induce the crystallization of n-type organic molecules at their sides, thus leading to the formation of laterally stacked p–n microbelts. Ambipolar OFETs based on the p–n heterojunction MB arrays exhibit balanced hole and electron mobilities of 0.32 and 0.43 cm2V−1s−1, respectively, enabling the fabrication of complementary-like inverters with large voltage gains. This work paves the way toward rational design and construction of single-crystalline organic p–n heterojunction arrays for high-performance organic, integrated circuits.

  • 022018
    邵智斌老师的论文被《材料人》报道
  • 022018
    邵智斌老师的论文"CdS Nanoribbon-Based Resistive Switches with Ultrawidely Tunable Power by Surface Charge Transfer Doping"发表在Adv. Funct. Mater.上
    Abstract 
    Traditional metal–insulator–metal (MIM)-based resistive switches (RS) possess a high operating current, which can be read directly without an amplifier yet will inevitably produce large power consumption. Rational control of the energy consumption of RS devices is surely desirable to achieve the energy-efficient purpose in a variety of practical applications. Here a surface charge transfer doping (SCTD) strategy is reported to manipulate the operating current as well as power consumption of the RS devices by using doped CdS nanoribbon (NR) as a rheostat. By controlling the concentration of surface dopant of MoO3, the conductivity of doped CdS NR can be tuned in a wide range of nine orders of magnitude, showing the transition from insulator to semiconductor and to conductor. On the basis of CdS NRs with controllable conductivity, the as-fabricated RS devices exhibit an ultrawidely tunable-power consumption from 1 nW, the lowest value reported so far, to 0.1 mW, which is close to the typical values of MIM-based RS devices. In view of the high controllability of the SCTD method, this work opens up unique opportunities for future energyefficient, performance-tunable, and multifunctional RS devices based on semiconductor nanostructures.

  • 022018
    丁可同学的论文"Hue tunable, high color saturation and high-efficiency graphene/silicon heterojunction solar cells with MgF₂/ZnS double anti-reflection layer"发表在 Nano Energy上
    Abstract
    Graphene/silicon (Gr/Si) heterojunctions with simple manufacturing process, high stability and excellent device performance have great potential in photovoltaic (PV) applications. In comparison to conventional PV panels with monotone colors, multi-color PV panels could be integrated in modern building facades and thus largely expand their application ranges. In this work, multi-color Gr/Si heterojunction PV devices were fabricated, for the first time, by taking advantage of the combination of ultra-thin highly transparent graphene and MgF2/ZnS anti-reflection coating. The double-layer film coating enabled the multi-color Gr/Si PV devices with both high color saturation and low optical loss. The PV devices exhibited respectable power conversion efficiency (PCE) in the range of 10.7–13.2%, depending on the color of the devices. In addition, PCE of the device with optimized anti-reflection coating reached as high as 14.6%, which is among the highest for the Gr/Si heterojunction solar cells. By varying the film thickness at different positions, a colored Gr/Si solar cell with visible pattern was made on a 2-in. Si wafer. Our work demonstrates the great potential of multi-colored Gr/Si solar cells for new-generation distributed solar energy systems with designable features.
  • 122017
    金向程同学的论文"Facile Assembly of High-quality Organic-inorganic Hybrid Perovskite Quantum Dot Thin Films for Bright Light-Emitting Diodes"发表在Adv. Funct.Mater.上
    Abstract
    Organic-inorganic hybrid perovskite (CH3NH3PbX3, X = Cl, Br or I) quantum dots (QDs) have shown superior optoelectronic properties and been regarded as one of the most ideal materials for next-generation optoelectronic devices, particularly for QDs-based light-emitting diodes (QLEDs). However, there are only a few reports on CH3NH3PbX3 QLEDs and the reported performance is still very poor, primarily due to the difficulites in the fabrication of high-quality compact QDs thin films from low-concentration QDs suspensions. In this work, we developed an electric-field-assisted (EFA) strategy for efficient fabrication of uniform CH3NH3PbBr3 QDs thin films with high photoluminescence quantum yields (PLQY, 80%-90%) from dilute CH3NH3PbBr3 QDs suspensions (~0.1 mg/mL) within 5 mins. Benefited from the high-qulity CH3NH3PbBr3 QDs thin films, the corresponding QLEDs delivered a highly bright green emission with maximum luminances of 12450 cd/m2. Furthermore, a current efficiency of 12.7 cd/A, a power efficiency of 9.7 lm/W, and an external quantum efficiency (EQE) of 3.2% were acheived by enhancing the hole injection. To our knowledge, the performance represents the best results for CH3NH3PbBr3 QDs-based QLEDs. These results indicate an important progress in the fabrication of high-performance CH3NH3PbX3 QLEDs and demonstrate their huge potential for the next-generation displays and lightings.

  • 122017
    邓巍同学发表在Nano Lett. 的论文“Ultrahigh-Responsivity Photodetectors from Perovskite Nanowire Arrays for Sequentially Tunable Spectral Measurement”入选了ACS Publication旗下Chemistry of Materials期刊,“Metal-Halide Perovskite Nanocrystals—A Bright Future for Optoelectronics”虚拟特刊。

    特刊网址:http://pubs.acs.org/page/vi/metalhalidperovskitenanocrystals.htm
  • 052017
    张业栋同学的论文"Precise Patterning of Organic Single Crystals via Capillary-Assisted Alternating-Electric Field "发表在small上
    Abstract
    Owing to the extraordinary properties, organic micro/nanocrystals are important building blocks for future low-cost and high-performance organic electronic devices. However, integrated device application of the organic micro/nanocrystals is hampered by the difficulty in high-throughput, high-precision patterning of the micro/nanocrystals. In this study, the authors demonstrate, for the first time, a facile capillary-assisted alternating-electric field method for the large-scale assembling and patterning of both 0D and 1D organic crystals. These crystals can be precisely patterned at the photolithography defined holes/channels at the substrate with the yield up to 95% in 1 mm. The mechanism of assembly kinetics is systematically studied by the electric field distribution simulation and experimental investigations. By using the strategy, various organic micro/nanocrystal patterns are obtained by simply altering the geometries of the photoresist patterns on substrates. Moreover, ultraviolet photodetectors based on the patterned Alq micro/nanocrystals exhibit visible–blind photoresponse with high sensitivity as well as excellent stability and reproducibility. This work paves the way toward high-integration, high-performance organic electronic, and optoelectronic devices from the organic micro/nanocrystals.

  • 022017
    邓巍同学的论文"Ultrahigh-Responsivity Photodetectors from Perovskite Nanowire Arrays for Sequentially Tunable Spectral Measurement"发表在Nano Lett.上
    Abstract
    Compared with polycrystalline films, single-crystalline methylammonium lead halide (MAPbX3, X = halogen) perovskite nanowires (NWs) with well-defined structure possess superior optoelectronic properties for optoelectronic applications. However, most of the prepared perovskite NWs exhibit properties below expectations due to poor crystalline quality and rough surfaces. It also remains a challenge to achieve aligned growth of single-crystalline perovskite NWs for integrated device applications. Here, we report a facile fluid-guided antisolvent vapor-assisted crystallization (FGAVC) method for large-scale fabrication of high-quality single-crystalline MAPb(I1-xBrx)3 (x = 0, 0.1, 0.2, 0.3, 0.4) NW arrays. The resultant perovskite NWs showed smooth surfaces due to slow crystallization process and moisture-isolated growth environment. Significantly, photodetectors made from the NW arrays exhibited outstanding performance in respect of ultrahigh responsivity of 12 500 A W-1, broad linear dynamic rang (LDR) of 150 dB, and robust stability. The responsivity represents the best value ever reported for perovskite-based photodetectors. Moreover, the spectral response of the MAPb(I1-xBrx)3 NW arrays could be sequentially tuned by varying the content of x = 0-0.4. On the basis of this feature, the NW arrays were monolithically integrated to form a unique system for directly measuring light wavelength. Our work would open a new avenue for the fabrication of high-performance, integrated optoelectronic devices from the perovskite NW arrays.
  • 022017
    课题组应邀为Adv. Mater.Tech. 撰写了题为"Ordered and Patterned Assembly of Organic Micro/Nanocrystals for Flexible Electronic and Optoelectronic Devices"的综述
    Abstract
    Organic semiconductor micro/nanocrystals (OSMCs) have attracted intensive research over the past few decades. Their unique electrical and mechanical properties afford them applications in a vast network of active flexible electronic and optoelectronic fields, such as organic field-effect transistors (OFETs), photodetectors (PDs), and organic light-emitting diodes (OLEDs) etc. However, the growth orientation and location of OSMCs are usually stochastic in nature, which hinders the further use of OSMCs in large-area plastic electronic devices. On the other hand, traditional microelectronic processing techniques like photolithography may damage the plastic substrates, polymer insulators, and organic materials. Thus the alignment and patterning of OSMCs and development of new device construction technologies are prerequisite for their flexible device applications in practice. In this progress report, we will highlight the important advancement for fabricating the aligned and patterned OSMCs, with a focus on their applications in next-generation flexible electronic and optoelectronic devices. Also, the challenges and outlooks of the ordered and patterned OSMCs in the flexible device applications are presented.

  • 012017
    刁森林同学的论文"12.35% efficient graphene quantum dots/silicon heterojunction solar cells using graphene transparent electrode"发表在Nano Energy上
    Abstract
    Zero-dimensional graphene quantum dots (GQDs) have lately intrigued intensive interest because of their great promise in energy, optoelectronic, and bio-imaging applications. Herein, we demonstrated the fabrication of highly efficient GQDs/n-silicon heterojunction solar cells via a simple solution process. Owing to the unique band structure, the GQDs layer could not only serve as hole transport layer to facilitate the separation of photo- generated electron-hole pairs, but also act as electron blocking layer to suppress the carrier recombination at anode. Moreover, graphene was used as the transparent top electrode for the heterojunction solar cells, ensuring the efficient light absorption and carrier collection. By adjusting the sizes of GQDs and the thickness of GQDs layer, a power conversion efficiency (PCE) as high as 12.35% under AM 1.5G irradiation was achieved, which represented a new efficiency record for this new-type solar cell. The devices also exhibited excellent stability in air due to the high chemical/physical stability of GQDs and graphene. The successful achievement of the high- efficiency GQDs/Si heterojunction solar cells opens up the opportunities for their potential applications in high- performance and low-cost photovoltaics.
  • 122016
    综述"Surface Charge Transfer Doping of Low-Dimensional Nanostructures toward High-Performance Nanodevices"以封面论文的形式发表在 Adv. Mater. 上
    Abstract
    Device applications of low-dimensional semiconductor nanostructures rely on the ability to rationally tune their electronic properties. However, the conven- tional doping method by introducing impurities into the nanostructures suf- fers from the low ef ciency, poor reliability, and damage to the host lattices. Alternatively, surface charge transfer doping (SCTD) is emerging as a simple yet ef cient technique to achieve reliable doping in a nondestructive manner, which can modulate the carrier concentration by injecting or extracting the carrier charges between the surface dopant and semiconductor due to the work-function difference. SCTD is particularly useful for low-dimensional nanostructures that possess high surface area and single-crystalline struc- ture. The high reproducibility, as well as the high spatial selectivity, makes SCTD a promising technique to construct high-performance nanodevices based on low-dimensional nanostructures. Here, recent advances of SCTD are summarized systematically and critically, focusing on its potential applica- tions in one- and two-dimensional nanostructures. Mechanisms as well as characterization techniques for the surface charge transfer are analyzed. We also highlight the progress in the construction of novel nanoelectronic and nano-optoelectronic devices via SCTD. Finally, the challenges and future research opportunities of the SCTD method are prospected.
                                                        
  • 122016
    夏斐斐老师的论文"Surface Charge Transfer Doping via Transition Metal Oxides for Efficient p-Type Doping of II-VI Nanostructures"发表在ACS Nano上
    Abstract
    Wide band gap II–VI nanostructures are important building blocks for new-generation electronic and optoelectronic devices. However, the difficulty of realizing p-type conductivity in these materials via conventional doping methods has severely handicapped the fabrication of p–n homojunctions and complementary circuits, which are the fundamental components for high-performance devices. Herein, by using first-principles density functional theory calculations, we demonstrated a simple yet efficient way to achieve controlled p-type doping on II–VI nanostructures via surface charge transfer doping (SCTD) using high work function transition metal oxides such as MoO3, WO3, CrO3, and V2O5 as dopants. Our calculations revealed that these oxides were capable of drawing electrons from II–VI nanostructures, leading to accumulation of positive charges (holes injection) in the II–VI nanostructures. As a result, Fermi levels of the II–VI nanostructures were shifted toward the valence band regions after surface modifications, along with the large enhancement of work functions. In situ ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy characterizations verified the significant interfacial charge transfer between II–VI nanostructures and surface dopants. Both theoretical calculations and electrical transfer measurements on the II–VI nanostructure-based field-effect transistors clearly showed the p-type conductivity of the nanostructures after surface modifications. Strikingly, II–VI nanowires could undergo semiconductor-to-metal transition by further increasing the SCTD level. SCTD offers the possibility to create a variety of electronic and optoelectronic devices from the II–VI nanostructures via realization of complementary doping.

  • 082016
    商其勋同学的论文被《Materials Views》亮点报道
  • 082016
    商其勋同学的论文"An Inherent Multifunctional Sellotape Substrate for High‐Performance Flexible and Wearable Organic Single‐Crystal Nanowire Array‐Based Transistors"发表在Adv. Electron. Mater.上
    Abstract

    Sellotape, as a flexible, sticky, and lightweight substrate, can be integrated in electronic devices to realize unprecedented and low-cost applications, such as biomedical devices, wearable electronics, smart clothes, and sensory skin for robotic system. However, very few works have successfully demonstrated fabricating devices on sellotape substrates, primarily because traditional microelectronic processing techniques, including photolithography, metalliza- tion, and lift-off, are incompatible with sellotape. Here a novel tape-stripping method is demonstrated for large-area fabrication of high-performance flexible and wearable organic nanowire array-based field-effect transistors (ONWFETs) on sellotape substrates. The copper phthalocyanine ONWFETs on the tapes exhibit high average mobility (≈1.02 cm2 V−1 s−1) as well as high bending and wearing stability. Furthermore, 3D ONWFET circuitry consisting of five vertically stacked layers is demonstrated. Device geometries and elec- tronic properties are maintained with high fidelity after sequential stacking processes. This is so far the first study of ONWFETs on flexible tapes and their applications in wearable or 3D integrated devices. It is anticipated that the novel tape stripping method may help overcome upcoming difficulties for organic flexible electronics.


  • 082016
    邓巍同学的论文被《X-MOL》报道
  • 072016
    毛杰同学的论文被《Materials Views》亮点报道
  • 042016
    张洪宾老师的论文"High-Responsivity, High-Detectivity, Ultrafast Topological Insulator Bi₂Se₃ /Silicon Heterostructure Broadband Photodetectors"发表在 ACS Nano 上
    Abstract

    As an exotic state of quantum matter, topological insulators have promising applications in new-generation electronic and optoelectronic devices. The realization of these applications relies critically on the preparation and properties understanding of high-quality topological insulators, which however are mainly fabricated by high-cost methods like molecular beam epitaxy. We here report the successful preparation of high-quality topological insulator Bi2Se3/Si heterostructure having an atomically abrupt interface by van der Waals epitaxy growth of Bi2Se3 films on Si wafer. A simple, low-cost physical vapor deposition (PVD) method was employed to achieve the growth of the Bi2Se3 films. The Bi2Se3/Si heterostructure exhibited excellent diode characteristics with a pronounced photoresponse under light illumination. The built-in potential at the Bi2Se3/Si interface greatly facilitated the separation and transport of photogenerated carriers, enabling the photodetector to have a high light responsivity of 24.28 A W–1, a high detectivity of 4.39 × 1012 Jones (Jones = cm Hz1/2 W–1), and a fast response speed of aproximately microseconds. These device parameters represent the highest values for topological insulator-based photodetectors. Additionally, the photodetector possessed broadband detection ranging from ultraviolet to optical telecommunication wavelengths. Given the simple device architecture and compatibility with silicon technology, the topological insulator Bi2Se3/Si heterostructure holds great promise for high-performance electronic and optoelectronic applications.

  • 042016
    邓巍同学的论文"Organometal Halide Perovskite Quantum Dots Light-Emitting Diodes"发表在 Adv. Funct. Mater. 上
    Abstract
    Organometal halide perovskites quantum dots (OHP-QDs) with bright, color-tunable, and narrow-band photoluminescence have significant advantages in display, lighting, and laser applications. Due to sparse concentrations and difficulties in the enrichment of OHP-QDs, production of large-area uniform films of OHP-QDs is a challenging task, which largely impedes their use in electroluminescence (EL) devices. Here, we report a simple dip-coating method to effectively fabricate large-area uniform films of OHP-QDs. Using this technique, we successfully produced multicolor OHP-QDs light-emitting diodes (OQ-LEDs) emitting in blue, blue-green, green, orange, and red color by simply tuning the halide composition or size of QDs. The blue, green and red OQ-LEDs exhibited, respectively, a maximum luminance of 2673, 2398, and 986 cd m-2 at a current efficiency of 4.01, 3.72, and 1.52 cd A-1, and an external quantum efficiency of 1.38%, 1.06%, and 0.53%, which are much better than most LEDs based on OHP films. The packaged OQ-LEDs show long-term stability in air (humidity~50%) for at least 7 days. The results demonstrate the great potential of the dip-coating method to fabricate large-area uniform films for various QDs. The high-efficiency OQ-LEDs also demonstrate the promising potential of OHP-QDs for low-cost display, lighting and optical communication applications.
  • 032016
    毛杰同学的论文"Ultrafast, Broadband Photodetector Based on MoSe₂/Silicon Heterojunction with Vertically Standing Layered Structure Using Graphene as Transparent Electrode"发表在Adv. Sci.上。
    Abstract

    Advances in the photocurrent conversion of layered molybdenum diselenide (MoSe2) have enabled the realization of a variety of important optoelectronic devices such as photovoltaics and photodetectors owing to its extraordinary properties. However,photodetectors based on MoSe2 mono-/multilayer sheets still suffer from low response speed and relatively weak light response arising from low light absorption. Herein, it is demonstrated that high-quality MoSe2/Si heterojunctions could be constructed by depositing n-type MoSe2 film on p-type Si substrate. The relatively thick MoSe2 film could offer strong light absorption from ultraviolet (UV) to visible and to near-infrared (NIR) light. Significantly, the MoSe2 film fabricated by sputtering possessed a vertically standing layered structure, greatly facilitating the separation and transport of photogenerated carriers. Collection of the carriers was further enhanced by the use of graphene (Gr) transparent electrode on the top. Owing to the unique device structure, the Gr/MoSe2/Si photodetectors exhibited outstanding device characteristics in terms of broadband response ranging from 365 to 1310 nm, high detectivity of 7.13 × 10^10 Jones, and ultrafast response speed of 270 ns. These parameters are significantly better than mono-/multilayer MoSe2-based photodetectors. Our work paves the way for development of high-performance optoelectronic devices based on MoSe2/Si heterojunctions.

  • 032016
    邓巍同学的论文"Aligned Single-Crystalline Perovskite Microwire Arrays for High-Performance Flexible Image Sensors with Long-Term Stability"发表在Adv. Mater.上
    Abstract
    A simple, low-cost blade-coating method is developed for the large-area fabrication of single-crystalline aligned CH3NH3PbI3 microwire (MW) arrays. The solution-coating method is applicable to flexible substrates, enabling the fabrication of MW-array-based photodetectors with excellent long-term stability, flexibility, and bending durability. Integrated devices from such photodetectors demonstrate high performance for high-resolution, flexible image sensors.

  • 012016
    综述"Two-dimensional layered material/silicon heterojunctions for energy and optoelectronic applications"发表在Nano Res.上
    Abstract
    As one of the most important semiconductor materials, silicon (Si) has been widely used in current energy and optoelectronic devices, such as solar cells and photodetectors. However, the traditional Si p–n junction solar cells need complicated fabrication processes, leading to the high cost of Si photovoltaic devices. The wide applications of Si-based photodetectors are also hampered by their low sensitivity to ultraviolet and infrared light. Recently, two-dimensional (2D) layered materials have emerged as a new material system with tremendous potential for future energy and optoelectronic applications. The combination of Si with 2D layered materials represents an innovative approach to construct high-performance optoelectronic devices by harnessing the complementary advantages of both materials. In this review, we summarize the recent advances in 2D layered material/Si heterojunctions and their applications in photovoltaic and optoelectronic devices. Finally, the outlook and challenges of 2D layered material/Si heterojunctions for high-performance device applications are presented.