Jiachen Zhou

Photodetectors Based on Organic–Inorganic Hybrid Lead Halide Perovskites

Abstract Recent years have witnessed skyrocketing research achievements in organic–inorganic hybrid lead halide perovskites (OIHPs) in the photovoltaic field. In addition to photovoltaics, more and more studies have focused on OIHPs‐based photodetectors in the past two years, due to the remarkable optoelectronic properties of OIHPs. This article summarizes the latest progress in this research field. To begin with, the factors influencing the performance of photodetectors are discussed, including both internal and external factors. In particular, the channel width and the incident power intensities should be taken into account to precisely and objectively evaluate and compare the output performance of different photodetectors. Next, photodetectors fabricated on single‐component perovskites in terms of different micromorphologies are discussed, namely, 3D thin‐film and single crystalline, 2D nanoplates, 1D nanowires, and 0D nanocrystals, respectively. Then, bilayer structured perovskite‐based photodetectors incorporating inorganic and organic semiconductors are discussed to improve the optoelectronic performance of their pristine counterparts. Additionally, flexible OIHPs‐based photodetectors are highlighted. Finally, a brief conclusion and outlook is given on the progress and challenges in the field of perovskites‐based photodetectors.

Facile Synthesis of a MoS2 and Functionalized Graphene Heterostructure for Enhanced Lithium-Storage Performance

A facile strategy was designed for the in situ synthesis of MoS2 nanospheres on functionalized graphene nanoplates (MoS2@f-graphene) for use as lithium-ion battery anode materials. A modified Birch reduction was used to exfoliate graphite into few-layer graphene followed by modification with functional groups. Compared to the most common approach of mixing MoS2 and reduced graphene oxide, our approach provides a way to circumvent the harsh oxidation and destruction of the carbon basal planes. In this process, alkylcarboxyl functional groups on the functionalized graphene (f-graphene) serve as sites where MoS2 nanospheres crystallize, and thus create bridges between the MoS2 nanospheres and the graphene layers to effectively facilitate electronic transport and to avoid both the aggregation of MoS2 and the restacking of graphene. As anode materials, this unique MoS2@f-graphene heterostructure has a high specific capacity of 1173 mAh g-1 at a current density of 100 mA g-1 and a good rate capacity (910 mAh g-1 at 1600 mA g-1).

Preparation of Advanced CuO Nanowires/Functionalized Graphene Composite Anode Material for Lithium Ion Batteries

The copper oxide (CuO) nanowires/functionalized graphene (f-graphene) composite material was successfully composed by a one-pot synthesis method. The f-graphene synthesized through the Birch reduction chemistry method was modified with functional group “–(CH2)5COOH”, and the CuO nanowires (NWs) were well dispersed in the f-graphene sheets. When used as anode materials in lithium-ion batteries, the composite exhibited good cyclic stability and decent specific capacity of 677 mA·h·g−1 after 50 cycles. CuO NWs can enhance the lithium-ion storage of the composites while the f-graphene effectively resists the volume expansion of the CuO NWs during the galvanostatic charge/discharge cyclic process, and provide a conductive paths for charge transportation. The good electrochemical performance of the synthesized CuO/f-graphene composite suggests great potential of the composite materials for lithium-ion batteries anodes.

Distinguishable Detection of Ultraviolet, Visible, and Infrared Spectrum with High-Responsivity Perovskite-Based Flexible Photosensors

Distinguishable detection of the ultraviolet, visible, and infrared spectrum is promising and significant for the super visual system of artificial intelligences. However, it is challenging to provide a photosensor with such broad spectral response ability. In this work, the ultraviolet, visible, and infrared spectrum is distinguished by developing serial photosensors based on perovskite/carbon nanotube hybrids. Oraganolead halide perovskites (CH3 NH3 PbX3 ) possess remarkable optoelectronic properties and tunable optical band gaps by changing the halogens, and integration with single-walled carbon nanotubes can further improve their photoresponsivities. The CH3 NH3 PbCl3 -based photosensor shows a responsivity up to 105 A W-1 to ultraviolet and no obvious response to visible light, which is superior to that of most ultraviolet sensors. The CH3 NH3 PbBr3 -based photosensor exhibits a high responsivity to visible light. Serial devices of the two hybrid photosensors with comparable electric and sensory performances can distinguish the spectrum of ultraviolet, visible, and infrared even with varying light intensities. The photosensors also demonstrate excellent mechanical flexibility and bending stability. By taking full advantages of the oraganolead halide perovskites, this work provides flexible high-responsivity photosensors specialized for ultraviolet, and gives a simple strategy for distinguishable detection of ultraviolet, visible, and infrared spectrum based on the serial flexible photosensors.

Performance improvement of organic phototransistors by using polystyrene microspheres

Organic phototransistors (OPTs) have been intensively studied in recent years due to the combined advantages of phototransistors and organic semiconductors (OSCs). However, the electrical performance of OPTs is largely limited by OSCs themselves, posing a challenge to further improve the performance of the devices. Preparing nano/micro-structures of OSCs is considered as an effective way to improve the performance of OPTs. Polystyrene (PS) microsphere, as a kind of insulating and low-cost material, is extensively used in fabricating nano/microporous structures, and the resulting devices exhibit high response to external stimuli. Therefore, we combined PS microspheres with OSCs to fabricate PS/OSC OPTs, and the Ilight/Idark ratio was enhanced by two orders of magnitude compared with the pristine counterparts, which can be modulated from 46 to 1800 by controlling the diameters of PS microspheres. This strategy paves a way for developing high-performance OPTs with nano/microporous structures with potential applications in organic optoelectronics.摘要有机光敏晶体管(OPTs)因结合了有机半导体和光敏晶体管的优势, 引起了科研工作者的广泛兴趣. 然而, OPTs性能很大程度上受限于有机半导体本身的性质, 这对进一步提高OPTs性能提出了挑战. 制备具有微纳结构的有机半导体被认为是提高器件性能的一种有效途径. 聚苯乙烯(PS)微球作为一种绝缘和低成本的材料, 可应用于制备微纳结构的器件, 使器件实现对外部刺激的超高响应. 本文中, 我们利用PS微球杂化有机半导体来制备具有微纳结构的OPTs, 使其光电流/暗电流(光灵敏度)提高了两个数量级, 并且通过调控PS微球的直径, 使光灵敏度从46增大到1800. 此研究结果为制备具有微纳孔结构的OPTs提供了新方法, 扩大了其在有机光电子中的应用.

Intrinsically ionic conductive cellulose nanopapers applied as all solid dielectrics for low voltage organic transistors

Biodegradability, low-voltage operation, and flexibility are important trends for the future organic electronics. High-capacitance dielectrics are essential for low-voltage organic field-effect transistors. Here we report the application of environmental-friendly cellulose nanopapers as high-capacitance dielectrics with intrinsic ionic conductivity. Different with the previously reported liquid/electrolyte-gated dielectrics, cellulose nanopapers can be applied as all-solid dielectrics without any liquid or gel. Organic field-effect transistors fabricated with cellulose nanopaper dielectrics exhibit good transistor performances under operation voltage below 2 V, and no discernible drain current change is observed when the device is under bending with radius down to 1 mm. Interesting properties of the cellulose nanopapers, such as ionic conductivity, ultra-smooth surface (~0.59 nm), high transparency (above 80%) and flexibility make them excellent candidates as high-capacitance dielectrics for flexible, transparent and low-voltage electronics.Next-generation organic electronics require flexible organic field effect transistors that show low-voltage operation and are biodegradable. Here, Huang and co-workers demonstrate high-performance transistors that utilize solid-state ionic conductive cellulose nanopaper as the dielectric.

Integration of Biomaterials into Sensors Based on Organic Thin-Film Transistors

Sensors based on organic thin-film transistors (OTFTs) present various advantages, including high sensitivity and mechanical flexibility, thus possessing potential applications such as wearable devices and biomedical electronics for health monitoring, etc. However, such applications are partially limited by the biocompatibility, biodegradability, and sensitivity to target analytes of OTFT-based sensors, which can be improved by the incorporation of diverse biomaterials. This article presents a brief review from the viewpoint of the type of the integrated biomaterials, including naturally occurring biomacromolecules such as proteins, enzymes, and deoxyribonucleic acid, as well as biocompatible polymers such as polylactide, poly(lactide-co-glycolide), poly(ethylene glycol), cellulose, polydimethylsiloxane, parylene, etc. It is believed that future work in this field should be devoted to the selectivity, sensitivity, and stability improvement as well as the high-level integration and sophistication on the basis of the OTFT-based sensors for physical, chemical, and biological sensing applications.