共查询到20条相似文献，搜索用时 15 毫秒
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An organic semiconductor thin film is a solid‐state matter comprising one or more molecules. For applications in electronics and photonics, several distinct functional organic thin films are stacked together to create a variety of devices such as organic light‐emitting diodes and organic solar cells. The energy levels at these thin‐film junctions dictate various electronic processes such as the charge transport across these junctions, the exciton dissociation rates at donor–acceptor molecular interfaces, and the charge trapping during exciton formation in a host–dopant system. These electronic processes are vital to a device's performance and functionality. To uncover a general scientific principle in governing the interface energy levels, highest occupied molecular orbitals, and vacuum level dipoles, herein a comprehensive experimental research is conducted on several dozens of organic–organic heterojunctions representative of various device applications. It is found that the experimental data map on interface energy levels, after correcting variables such as molecular orientation‐dependent ionization energies, consists of three distinct regions depending on interface fundamental physical parameters such as Fermi energy, work function, highest occupied molecular orbitals, and lowest unoccupied molecular orbitals. This general energy map provides a master guide in selection of new materials for fabricating future generations of organic semiconductor devices. 相似文献
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Qinye Bao Slawomir Braun Chuanfei Wang Xianjie Liu Mats Fahlman 《Advanced Materials Interfaces》2019,6(1)
In this short review the energy level alignment of interfaces involving solution‐processed conjugated polymer (and soluble small molecules) films is described. Some general material properties of conjugated polymers and their solution‐processed films are introduced, and the basic physics involved in energy level alignment at their interfaces is then discussed. An overview of energy level bending in (ultra)thin conjugated polymer films (often referred to as “band bending”) is given and the effects of ion‐containing interlayers typically used in organic electronic devices such as polymer light emitting diodes and organic bulk heterojunction solar cells are explored. The review finishes by describing a few of the available computational models useful for predicting and/or modeling energy level alignment at interfaces of solution‐processed polymer films and discusses their respective strengths and weaknesses. 相似文献
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Jiaxin Hu Nabi Aghdassi Shubham Bhagat Yves Garmshausen Rongbin Wang Norbert Koch Stefan Hecht Steffen Duhm Ingo Salzmann 《Advanced Materials Interfaces》2020,7(3)
It is shown that fluorination of para‐sexiphenyl (6P) at the meta‐ or ortho‐positions of one terminal phenyl ring, as well as the addition of a terminal cyano‐group has an eminent impact on both growth and electronic properties of thin films. X‐ray diffraction techniques indicate that films of meta‐substituted 6P (m‐2F‐6P) develop a smooth, layered structure showing crystalline order within the layers only. Contrary, both ortho‐substituted (o‐2F‐6P) and cyano‐substituted 6P (CN‐6P) form films of 3D crystalline order. The correlation of structural information with data from ultraviolet photoelectron spectroscopy reveals that m‐2F‐6P and CN‐6P do not show preferentially oriented dipoles in the film, while o‐2F‐6P grows with collective downward orientation of the dipole moments. The subtle difference in substitution position has a dramatic impact on the thin‐film ionization energy, which increases from 5.40 (ortho) to 6.80 eV (meta) and reaches even 7.50 eV for CN‐6P. The present study shows that nonsymmetric substitution, which induces molecular dipole moments via intramolecular polar bonds, strongly impacts structure, morphology, and electronic properties of thin films. Thusly modifying common conjugated organic materials represents a valuable tool to establish smooth, crystalline layers with altered energetics at hetero‐interfaces with organic or electrode materials in electronic devices. 相似文献
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《Advanced Materials Interfaces》2017,4(2)
Metal halide perovskites, a class of crystalline semiconductors with unique optical and electronic properties, are emerging as potential solutions for low‐cost photovoltaics and photonic sources in fields of solar cells, sensors, light‐emitting diodes and lasers. Regardless of significant progress on device efficiency with the control over perovskite structures and film morphologies, unveiling the interface energetics and band alignment of these perovskite systems is indispensable for the performance optimization in the optoelectronic applications by grasping the photon harvest and charge transport processes. Herein we review the recent advances in the energetics of metal halide perovskite interfaces. The electronic properties of perovskite materials are addressed in terms of halide substitution, thermal annealing and substrate effects as well as trap states. The energy level alignments of interfaces between perovskite films and charge transport layers are then discussed, which is correlated to the photovoltaic properties in perovskite solar cells. 相似文献
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Riming Nie Xianyu Deng Lei Feng Guiguang Hu Yangyang Wang Gang Yu Jianbin Xu 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(24)
Photodetectors with high photoelectronic gain generally require a high negative working voltage and a very low environment temperature. They also exhibit low response speed and narrow linear dynamic range (LDR). Here, an organic photodiode is demonstrated, which shows a large amount of photon to electron multiplication at room temperature with highest external quantum efficiency (EQE) from ultraviolet (UV) to near‐infrared region of 5.02 × 103% (29.55 A W?1) under a very low positive voltage of 1.0 V, accompanied with a fast response speed and a high LDR from 10?7 to 101 mW cm?2. At a relatively high positive bias of 10 V, the EQE is up to 1.59 × 105% (936.05 A W?1). Inversely, no gain is found at negative bias. The gain behavior is exactly similar to a bipolar phototransistor, which is attributed to the photoinduced release of accumulated carriers. The devices at a low voltage exhibit a normalized detectivity (D *) over 1014 Jones by actual measurements, which is about two or three order of magnitudes higher than that of the highest existing photodetectors. These pave a new way for realization of high sensitive detectors with fast response toward the single photon detection. 相似文献
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Tingting Yan Wei Song Jiaming Huang Ruixiang Peng Like Huang Ziyi Ge 《Advanced materials (Deerfield Beach, Fla.)》2019,31(39)
Ternary heterojunction strategies appear to be an efficient approach to improve the efficiency of organic solar cells (OSCs) through harvesting more sunlight. Ternary OSCs are fabricated by employing wide bandgap polymer donor (PM6), narrow bandgap nonfullerene acceptor (Y6), and PC71BM as the third component to tune the light absorption and morphologies of the blend films. A record power conversion efficiency (PCE) of 16.67% (certified as 16.0%) on rigid substrate is achieved in an optimized PM6:Y6:PC71BM blend ratio of 1:1:0.2. The introduction of PC71BM endows the blend with enhanced absorption in the range of 300–500 nm and optimises interpenetrating morphologies to promote photogenerated charge dissociation and extraction. More importantly, a PCE of 14.06% for flexible ITO‐free ternary OSCs is obtained based on this ternary heterojunction system, which is the highest PCE reported for flexible state‐of‐the‐art OSCs. A very promising ternary heterojunction strategy to develop highly efficient rigid and flexible OSCs is presented. 相似文献
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