Rational Mutual Interactions in Ternary Systems Enable High-Performance Organic Solar Cells

Ternary organic solar cells (TOSCs) offer a facile and efficient approach to increase the power conversion efficiencies (PCEs). However, the critical roles that guest components play in complicated ternary systems remain poorly understood. Herein, two acceptors named LA1 and LA9 with differing crystallinity are investigated. The overly crystalline LA9 induces large self-aggregates in PM6:LA9 binary system, resulting in a lower PCE (13.12%) compared to PM6:LA1 device (13.89%). Encouragingly, both acceptors are verified as efficient guest candidates into the host binary PM6:NCBDT-4Cl (PCE = 13.48%) and afford markedly improved PCEs up to 15.39% and 15.75% in LA1 and LA9 ternary devices, respectively. Interestingly, the higher crystallinity LA9 reveals smaller interaction energies with both the host acceptor and donor PM6. Compared to LA1, the appropriate mutual interactions in the LA9 ternary system not only induces the orderly crystallinity of PM6 but also better compatibility with the host acceptor, generating further optimized molecular orientations and ternary morphology. Therefore, enhanced charge transport and minimized recombination loss are detected in LA9 ternary devices, affording the most competitive performance among Y6-sbsent TOSCs. This work suggests that complicated intermolecular interactions should be seriously considered when fabricating state-of-the-art multiple components OSCs.     

Organic Semiconductor Optical Amplifiers

Organic semiconducting materials have been researched for novel optoelectronic devices due to their efficient light emission and high gain properties. Such devices range from organic light-emitting diodes and solar cells to lasers and amplifiers. This paper explores the research carried out on one of these devices: organic semiconductor amplifiers that have shown to give high gains of 20–40 dB in solution and solid state.      

Twisted Crystalline Organic Semiconductor Photodetectors

Optoelectronic properties of anisotropic crystals vary with direction requiring that the orientation of molecular organic semiconductor crystals is controlled in optoelectronic device active layers to achieve optimal performance. Here, a generalizable strategy to introduce periodic variations in the out-of-plane orientations of 5,11-bis(triisopropylsilylethynyl)anthradithiophene (TIPS ADT) crystals is presented. TIPS ADT crystallized from the melt in the presence of 16 wt.% polyethylene (PE) forms banded spherulites of crystalline fibrils that twist in concert about the radial growth direction. These spherulites exhibit band-dependent light absorption, photoluminescence, and Raman scattering depending on the local orientation of crystals. Mueller matrix imaging reveals strong circular extinction (CE), with TIPS ADT banded spherulites exhibiting domains of positive or negative CE signal depending on the crystal twisting sense. Furthermore, orientation-dependent enhancement in charge injection and extraction in films of twisted TIPS ADT crystals compared to films of straight crystals is visualized in local conductive atomic force microscopy maps. This enhancement leads to 3.3- and 6.2-times larger photocurrents and external quantum efficiencies, respectively, in photodetectors comprising twisted crystals than those comprising straight crystals.     

有机半导体电注入激光器

有机半导体激光器实现了从光泵浦到电泵浦。回顾了有机半导体激光器从光泵浦到电流入的发展过程。概述了有机半导体材料产生激光的特性,介绍了贝尔实验室第一个有机固态电注入型激光器的工作原理,提出了在器件结构上的一些新设想。     

Organic Semiconductor Nanotubes for Electrochemical Devices

Electrochemical devices that transform electrical energy to mechanical energy through an electrochemical process have numerous applications ranging from robotics and micropumps to microlenses and bioelectronics. To date, achievement of large deformation strains and fast responses remains challenging for electrochemical actuators wherein drag forces restrict the device motion and electrode materials/structures limit the ion transportation. Results for electrochemical actuators, electrochemical mass transfers, and electrochemical dynamics made from organic semiconductors (OSNTs) are reported. The OSNTs device exhibits high-performance with fast ion transport and accumulation in liquid and gel-polymer electrolytes. This device demonstrates an impressive performance, including low power consumption/strain, a large deformation, fast response, and excellent actuation stability. This outstanding performance stems from the enormous effective surface area of nanotubes that facilitates ion transport and accumulation resulting in high electroactivity and durability. Experimental studies of motion and mass transport are utilized along with the theoretical analysis for a variable–mass system to establish the dynamics of the device and to introduce a modified form of Euler-Bernoulli's equation for the OSNTs. Ultimately, a state-of-the-art miniaturized device composed of multiple microactuators for potential biomedical applications is demonstrated. This work provides new opportunities for next-generation actuators that can be utilized in artificial muscles and biomedical devices.     

有机半导体器件的现状及发展趋势

从上世纪末和本世纪初开始,有机半导体材料研究引起了业界的广泛重视,使有机半导体器件的实验室制作水平得到大幅提高,并逐步进入当前的商品发展阶段。概述了有机半导体的发展历程、各种器件结构与特性及其技术现状;介绍了有机发光二极管(OLED)、太阳电池以及其他有机半导体器件的应用概况;探讨了有机半导体优于Si和GaAs等典型无机半导体技术的特点,分析讨论了有机半导体技术的发展前景;指出有机半导体器件有望成为解决传统半导体技术问题的有效途径。     

单层有机半导体微腔效应的研究

制作了ＤＢＲ／ＩＴＯ／ＰＰＶ／Ａ１微腔结构，研究了这种结构ＰＰＶ发光器件的光致发光和电致发光特性。实验结果表明，由简单地调节夹于两金属电极镜面之间的ＰＰＶ层厚度可实现微腔效应。     

Manipulating Organic Semiconductor Morphology with Visible Light

A method is presented to manipulate the final morphology of roll-to-roll slot-die coated poly(3-hexylthiophene) (P3HT) by optically exciting the p-type polymer in solution while coating. These results provide a comprehensive picture of the entire knowledge chain, from demonstrating how to apply the authors’ method to a fundamental understanding of the changes in morphology and physical properties induced by exciting P3HT while coating. By combining results from density functional theory and molecular dynamics simulations with a variety of X-ray experiments, absorption spectroscopy, and THz spectroscopy, the relationship between morphology and physical properties of the thin film is demonstrated. Specifically, in P3HT films excited with light during deposition, changes in crystallinity and texture with more face-on orientation and increased out-of-plane charge mobility are observed.     

有机半导体薄膜三极管的研制

采用真空蒸镀法和有机半导体材料酞菁铜,制作Au/CuPc/Al/ CuPc/Au三明治结构的肖特基型栅极有机静电感应三极管.该三极管导电沟道垂直于CuPc薄膜,与采用MOSFET结构的有机薄膜三极管相比导电沟道大幅缩短,有利于克服有机半导体电学性能的缺点.实验结果表明,该三极管驱动电压低,呈不饱和电流-电压特性.其工作特性依赖于栅极电压和梳状铝电极的结构.通过合理设计、制作梳状铝电极,获得了良好的三极管静态、动态特性.     

有机半导体材料蒽薄膜的生长

利用常规的真空蒸发技术,在热氧化硅片的衬底上沉积了蒽薄膜.用扫描电子显微镜(SEM)和原子力显微镜(AFM)对不同沉积时间的蒽薄膜形貌进行了观察,研究了蒸发沉积蒽膜时膜在二氧化硅衬底上的成核和生长模式,并借助X射线衍射仪(XRD)分析了薄膜的结晶状态.结果显示:蒽膜生长时,蒽的临界核以Volmer-Weber模式生长,即蒽首先形成许多三维岛状的晶核,核长大增高为岛,然后在蒽离域大π键的作用下,相邻的两层蒽分子存在一定程度的交叠,岛与岛相互连接构成岛的通道,最后形成均匀致密、具有良好晶体特性的多晶薄膜.     

Diarylfluorene-Based Organic Semiconductor Materials toward Optoelectronic Applications

Modular production is a convenient strategy that not only realizes the mass production of conjugated materials, but also precisely regulates their photoelectrical property for optoelectronic applications. Diarylfluorene is a functional building block in constructing organic semiconductors arising from its special electronic, spacial, and conformational structure. Because of easy chemical modification, tunable electronic structure, and high photoluminescence quantum yield, diarylfluorene-based conjugated materials have undergone remarkable development in variety of low-cost optoelectronic devices. Herein, the authors present an overview mainly to describe the recent research progresses of diarylfluorene-based molecules, including 9,9′-diarylfluorene, heteroatom-containing spirocyclic diarylfluorene, and 4-position substituted 9,9′-diarylfluorene. The synthetic routes, molecular structures as well as their diverse applications toward optoelectronic devices are introduced and summarized systematically. Finally, the future challenges and development are also discussed in this vital research field.     

有机半导体研究进展

1977年人们发现通过掺杂可以使聚乙炔膜的电导率提高 1 2个量级 ,由绝缘体变成导体 ,从此掀起了有机半导体的研究热潮。其研究工作包括有机高分子材料、有机小分子材料和有机分子晶体材料的电学、光学等性质。有机半导体中的载流子除了电子和空穴外 ,还有孤子、极化子等。人们已经获得低温迁移率高达 1 0 5cm2 /V.s的高质量有机半导体晶体 ,在其中观察到量子霍尔效应 ,并用其制成有机半导体激光器。如今有机半导体彩色显示屏已进入实用阶段。     

有机半导体薄膜三极管的研制

采用真空蒸镀法和有机半导体材料酞菁铜,制作Au/CuPc/Al/ CuPc/Au三明治结构的肖特基型栅极有机静电感应三极管.该三极管导电沟道垂直于CuPc薄膜,与采用MOSFET结构的有机薄膜三极管相比导电沟道大幅缩短,有利于克服有机半导体电学性能的缺点.实验结果表明,该三极管驱动电压低,呈不饱和电流-电压特性.其工作特性依赖于栅极电压和梳状铝电极的结构.通过合理设计、制作梳状铝电极,获得了良好的三极管静态、动态特性.     

Exciton‐Charge Annihilation in Organic Semiconductor Films

Time‐resolved optical spectroscopy is used to investigate exciton‐charge annihilation reactions in blended films of organic semiconductors. In donor–acceptor blends where charges are photogenerated via excitons, pulsed optical excitation can deliver a sufficient density of temporally overlapping excitons and charges for them to interact. Transient absorption spectroscopy measurements demonstrate clear signatures of exciton‐charge annihilation reactions at excitation densities of ≈10¹⁸ cm^?3. The strength of exciton‐charge annihilation is consistent with a resonant energy transfer mechanism between fluorescent excitons and resonantly absorbing charges, which is shown to generally be strong in organic semiconductors. The extent of exciton‐charge annihilation is very sensitive not only to fluence but also to blend morphology, becoming notably strong in donor–acceptor blends with nanomorphologies optimized for photovoltaic operation. The results highlight both the value of transient optical spectroscopy to interrogate exciton‐charge annihilation reactions and the need to recognize and account for annihilation reactions in other transient optical investigations of organic semiconductors.     

Structure/Property Control in Photocatalytic Organic Semiconductor Nanocrystals

Photocatalysis offers a practical solution to the ever increasing energy and environmental issues by using a semiconductor to harvest freely available sunlight. Photoactive organic semiconductor nanocrystals (OSNs) are promising photocatalysts due to their structure and function which are easily tunable by molecular design. Extensive studies have yielded significant progress on OSNs in terms of photoresponse, charge carrier mobility, as well as photoconversion efficiency. This review provides a comprehensive discussion of the emerging crystal and interface engineering strategies used in optimizing structure/property of OSNs. The basic mechanisms involved in organic photocatalysis are discussed, for a better understanding of its dependence on the molecular and supramolecular structures. Then, the intermolecular interactions in molecular packing and the kinetic and thermodynamic control over the crystal growth process are summarized, with the aim of tuning the optical and electrical properties. Band energy alignment, charge carrier dynamics, and charge transfer are discussed in different heterostructures. In each case, structure/property relationships and how to tune them are emphasized. Finally, challenges and opportunities for the practical use of the organic photocatalysts are discussed.     

Current-Mode Logic in Organic Semiconductor Based on Source-Gated Transistors

Due to the low mobility and the abundance of trap states in organic field-effect transistors (OFETs), the operation of conventional logic circuits-based OFETs needs a large voltage swing, and suffers large switching noise and low speed. In this letter, current-mode logic (CML) circuits composed of organic source-gated transistors (OSGTs) are proposed for high-speed signaling based on existing material and process technologies. Mixed-mode simulations show that CML circuits using simple resistive loads can still be operated much faster than an ideal conventional inverter with perfect active loads and OFETs free of traps. With the same supply voltage and device parameters, CML circuits can work with a wide range of signal swings. The superior analog performance of OSGTs is also shown to fit well with the design requirements for CML circuits in terms of low power supply, high output impedance, and stability.      

Understanding Photocapacitive and Photofaradaic Processes in Organic Semiconductor Photoelectrodes for Optobioelectronics

Photoactive organic semiconductor substrates are envisioned as a novel class of bioelectronic devices that transduce light into stimulating biological signals with relevance for retinal implants or guided cellular differentiation. The direct interface between the semiconductor and the electrolyte gives rise to different competing optoelectronic transduction mechanisms. A detailed understanding of such faradaic or capacitive processes and the underlying material science is necessary to develop and optimize future devices. Here, the problem in organic photoelectrodes is addressed based on a planar p-n junction containing phthalocyanine (H₂Pc) and N,N′-dimethyl perylenetetracarboxylic diimide (PTCDI). The detailed characterization of photoelectrochemical current transients is combined with spectroscopic measurements, impedance spectroscopy, and local photovoltage measurements to establish a model that predicts quantitatively faradaic or capacitive current transients. The decisive elements of the model are the energy levels present at the interface and the voltage building up in the photoelectrode. The result of the efforts is a comprehensive model of photocapacitive and photofaradaic effects that can be applied to developing wireless bioelectronic photostimulation devices.     

Laboratory Thin-Film Encapsulation of Air-Sensitive Organic Semiconductor Devices

We present an approach, which is compatible with both glass and polymer substrates, to in-laboratory handling and intra-laboratory shipping of air-sensitive organic semiconductors. Encapsulation approaches are presented using polymer/ceramic and polymer/metal thin-film barriers using commercially available materials and generally available laboratory equipment. A technique for depositing an opaque vapor barrier, a transparent vapor barrier, and an approach to storing and shipping air-sensitive thin-film organic semiconductor devices on both polymer and glass substrates are presented. Barrier performance in air was tested using organic light-emitting diodes (OLEDs) as test devices. The half-life performance of OLEDs on plastic substrates in air exceeded 700 h, and that on glass exceeded 500 h. Commercially available heat-seal barrier bag systems for device shipping and storage in air were tested using a thin film of metallic calcium to test water permeation. More than four months of storage of a metallic calcium film in a heat-sealed foil bag was demonstrated in the best storage system. These approaches allow for the encapsulation of samples for longer duration testing and transportation than otherwise possible.     

有机半导体材料并五苯薄膜的生长

优化有机晶体的生长工艺是获得性能优良的有机场效应管(OFET)的重要基础。以热氧化后的硅片为衬底,用真空蒸镀的方法制备了有机半导体材料并五苯薄膜,通过X射线衍射和原子力显微镜对薄膜的生长晶体结构及形貌等进行了分析,讨论了薄膜制备过程中的诸多因素对晶体生长的影响。     

有机半导体薄膜层的图形化方法

对有机半导体层的图形化方法进行了详细介绍.对比分析了非传统有机半导体薄层的图形化方法和与传统光刻技术类似的有机层图形化方法,指出了各种方法的适用范围及其优缺点.