高结晶性小分子给体材料应用于全小分子有机太阳能电池中的研究进展

随着新型小分子给体材料和非富勒烯小分子受体材料的开发和应用, 非富勒烯全小分子有机太阳能电池(NF-ASM OSCs)的光电转换效率已经突破15%, 并逐渐接近聚合物太阳能电池的效率. 相比于聚合物电子给体材料, 小分子电子给体材料拥有其独特的优势, 例如合成批次性差异小、分子量明确和易于提纯等; 但是, 对小分子给体材料的结晶性难于精确调控, 使获得合适的纳米级结构的混合膜仍然是一个挑战. 本综述以给体小分子中心共轭单元的扩展为主线, 从分子设计的角度汇总了近年来对苯并二噻吩、萘并二噻吩和二噻并苯并二噻吩类小分子给体材料的结晶性研究, 并为进一步改善电池活性层形貌和获得更高的光伏性能提供了未来发展的建议.     

小分子给体/高分子受体型有机太阳能电池研究进展

有机太阳能电池具有低成本、柔性和质量轻等优势,是一种有应用前景的光伏技术,受到人们的广泛关注.有机太阳能电池的光敏活性层通常由p-型有机半导体(包括小分子和高分子)与n-型有机半导体(包括小分子和高分子)共混而成.小分子给体/高分子受体型有机太阳能电池具有形貌热稳定性优异的特点,值得深入研究.本综述旨在总结小分子给体/高分子受体型有机太阳能电池的研究进展,分别介绍了基于酰亚胺基、氰基和含硼氮配位键(B←N)的高分子受体的活性层材料体系的发展状况.在器件性能方面,通过分子设计、相分离形貌调控,改善了小分子给体/高分子受体的匹配性,将该类电池的能量转换效率从最初的0.29%提升至目前的9.51%,为性能的进一步提升总结了经验;在稳定性方面,基于该体系形貌热稳定性优异的特点,开发出高温耐受型有机太阳能电池器件.最后,展望了小分子给体/高分子受体型有机太阳能电池的未来发展方向和前景.     

基于非富勒烯受体的溶液加工型全小分子太阳能电池研究进展

有机太阳能电池(OPV),具有质量轻、可成本低制备等优势,是一种具有实际应用潜力的光伏技术。有机太阳能电池活性层可以由共轭聚合物或溶液可加工的小分子材料(给体与受体)共混组成。由于小分子材料具有明确的分子结构,纯度可控及无批次差别影响的特点;并结合近年来非富勒烯小分子受体的快速发展,使得非富勒烯全小分子(NF-SM-OPV)电池研究受到广泛关注。由于大部分A-D-A型非富勒烯受体分子具有各向异性的特点,这使激子解离和电荷传输,很大程度上受分子间堆积方式的影响,导致非富勒烯全小分子电池活性层形貌调控更加复杂。虽然非富勒烯小分子太阳能电池具有非富勒烯受体材料和小分子材料的双重优势,但高效率非富勒烯小分子太阳能电池的制备,仍具有很大挑战。因此,本文总结近年来高性能非富勒烯小分子太阳能电池的相关进展。着重介绍针对非富勒烯受体的给体小分子材料设计工作,并在此基础上近一步讨论非富勒烯小分子太阳能电池面临的挑战与展望。     

基于小分子噻吩单元的有机太阳能电池研究进展

噻吩及衍生物基团具有独特的光电性能,已广泛应用于有机太阳能电池的设计与合成中,并在有机光电领域发挥着重要的作用。本文综述了近几年来含有噻吩及其衍生物的有机小分子太阳能电池的研究进展。分别综述了含联噻吩、苯并二噻吩和二噻吩并噻咯单元的“给体 受体 给体”型有机供体小分子,并总结了其结构差异。从分子设计的角度出发,探讨分子骨架的共轭程度、链端基团、中心构筑单元数目等改变对材料的光学吸收、能级水平、迁移率等性能的影响,总结了设计高性能的小分子供体材料有效的途径。     

有机太阳能电池材料研究新进展

介绍了有机太阳能电池研究的背景、基本原理、分类,并对有机太阳能电池材料进行了全面综述,包括小分子太阳能电池材料、大分子太阳能电池材料、D-A体系材料和有机无机杂化体系材料.     

基于卟啉的新型近红外非富勒烯电子受体分子

正有机太阳能电池因其质轻、柔性和可溶液加工等优点而具有潜在应用前景1。有机太阳能电池的性能主要取决于活性层对光的吸收和转换过程,因此活性层材料的开发成为研究关键。当前活性层主要采用由给体和受体共混的本体异质结结构,其中大量高性能的共轭高分子和小分子给体     

苯并二噻吩基小分子高效有机太阳能电池研究进展

有机太阳能电池(organic solar cell,OSC)是由有机材料构成活性层的太阳能电池.苯并[1,2-b:4,5-b']二噻吩(benzo[1,2-b:4,5-b']dithiophene,BDT)由于具有较大的刚性平面共轭结构,可以显著提高π电子的离域能力和分子间的π-π相互作用,且易化学修饰,合成方便,成为太阳能电池给体材料研究中的一个"明星分子"单元.目前,已报道的基于BDT共轭单元的有机光伏器件(organic photovoltaic device,OPV)的光电转化效率(power conversion efficiency,PCE)最高已达到9.95%,应用前景巨大.综述了BDT基小分子有机太阳能电池(small molecule organic solar cell,SM-OSC)活性层材料近年来的研究进展,并简要分析了小分子由于主链、侧链、封端基团的差异对器件性能的不同影响.     

非富勒烯类有机小分子受体材料

在本体异质结太阳能电池的研究过程中,异质结活性层材料的发展一直是最基本最核心的部分,活性层材料包括给体材料和受体材料,其中给体材料的研究一直占据着主导地位,很多课题组报道的器件效率已经超过8%;而受体材料的研究却相对单一,大部分研究都围绕富勒烯及其衍生物.近年来非富勒烯类的有机小分子受体材料由于其易于合成与纯化、通过分子设计使能级更方便调节等优点引起了人们的广泛关注并且取得了很大进展,目前以它作为受体材料的电池效率可以达到4%.综述了近年来几类非富勒烯类有机小分子受体材料的研究进展,包括它们的分子设计及其在光伏器件中的应用,最后我们讨论了提高非富勒烯类的有机小分子受体材料器件性能的关键因素及其研究前景.     

苯并噻二唑类有机太阳能电池材料研究进展

苯并噻二唑结构单元被广泛用来构建高光电转换效率的有机太阳能电池材料.从聚合物太阳能电池、有机小分子太阳能电池以及染料敏化太阳能电池三个方面系统地综述了近年来含苯并噻二唑基团的有机太阳能电池材料的研究进展,并对其发展趋势和应用前景做了展望.     

可溶液加工的D-A-D型有机小分子的烷基链效应及光电性能

设计合成了3种可溶液加工的基于噻吩给体和2-吡喃-4-亚基丙二氰(PM)受体的新型Donor-Acceptor-Donor(D-A-D)型有机小分子TPT-N, TPT-S和TPT-D. 研究了噻吩给体单元上烷基链的数目对分子的溶解性、 光物理(吸收特性)、 热稳定和光电性能的影响. 结果表明, 随着烷基链的增加, 分子的溶解性增加, 成膜性能提高; 分子在溶液中的吸收光谱发生红移, 薄膜的吸收谱带变窄, 分子的最高占有分子轨道(HOMO)能级提高. 以D-A-D型有机小分子为给体, 富勒烯C₆₀衍生物-苯基-C₆₁-丁酸甲酯(PCBM)为受体制备了结构为ITO/PEDOT∶PSS/D-A-D∶PCBM/LiF/Al的体异质结太阳能电池. 研究结果表明, 基于单烷基链的TPT-S的太阳能电池具有相对较高的能量转换效率. 说明在D-A-D型有机小分子太阳能电池材料中, 烷基链的数目是决定材料性能及器件性能的重要因素之一.     

A new donor-acceptor molecule with uniaxial anisotropy for efficient vacuum-deposited organic solar cells

A new D-π-A molecule (TPDCDTS) adopting coplanar diphenyl-substituted dithienosilole as a central π-bridge of triphenylamine (donor) and dicyanovinylene (acceptor) has been synthesized as donor material for small molecule organic solar cells (SMOSC) incorporating C(70) as an acceptor showed an appreciable power conversion efficiency of 3.82%.     

A Solution‐Processable Molecule using Thieno[3,2‐b]thiophene as Building Block for Efficient Organic Solar Cells

A solution‐processed acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) type small molecule, namely DCATT, has been designed and synthesized for the application as donor material in organic solar cells. The fused aromatic unit thieno[3,2‐b]thiophene (TT) flanked with thiophene is applied as π bridge, while 4,8‐bisthienyl substituted benzodithiophene (BDT) and 2‐ethylhexyl cyanoacetate are chosen as the central building block and end group, respectively. Introduction of fused ring to the small molecule enhances the conjugation length of the main chain, and gives a strong tendency to form π–π stacking with a large overlapping area which favors to high charge carrier transport. Small‐molecule organic solar cells based on blends of DCATT and fullerene acceptor exhibit power conversion efficiencies as high as 5.20 % under the illumination of AM 1.5G, 100 mW cm^?2.     

Organic solar cells based on small molecule donor and polymer acceptor

Small molecule donor/polymer acceptor(SD/PA)-type organic solar cells(OSCs) have attracted widespread attention in recent years due to the continuing power conversion efficiency(PCE) growth, near 10%, and the excellent thermal stability for the practical applications. However, the development of SD/PA-type OSCs lags far behind that of polymer donor/small molecule acceptor(PD/SA)-type OSCs, which are also based on the combination of small molecule and polymer, with the PCEs exceeding 18%. The rea...     

Naphthodithiophene-based donor materials for solution processed organic solar cells

As an emerging donor building block, naphthodithiophene (NDT) is causing more concerns in the field of organic semiconductors. With the rigid and coplanar molecule structure, NDT will exhibit more application space relying on its own advantage for facilitating the charge carrier transport. In this review article, we have summarized the development progress on the NDT-based donor materials for solution processed organic solar cells. Discussions and comments on those representative NDT type materials about structure and property are also presented.     

Effects of subtle change in side chains on the photovoltaic performance of small molecular donors for solar cells

Small-molecule organic solar cells (SMOSCs) have attracted considerable attention owing to the merits of small molecules, such as easy purification, well-defined chemical structure. To achieve high-performance SMOSCs, the rational design of well-matched donor and acceptor materials is extremely essential. In this work, two new small molecular donor materials with subtle change in the conjugated side thiophene rings are synthesized. The subtle change significantly affects the photovoltaic performance of molecular donors. Compared with chlorinated molecule MDJ-Cl, the non-chlorinated analogue MDJ exhibits decreased miscibility with the non-fullerene acceptor Y6, can more efficiently quench the excitons of Y6. As a result, a improved PCE of 11.16% is obtained for MDJ:Y6 based SMOSCs. The results highlight the importance of fine-tuning the molecular structure to achieve high-performance SMOSCs.     

Layer-by-Layer Organic Solar Cells Enabled by 1,3,4-Selenadiazole-Containing Crystalline Small Molecule with Double-Fibril Network Morphology

A double-fibril network of the photoactive layer morphology is recognized as an ideal structure facilitating exciton diffusion and charge carrier transport for high-performance organic solar cells (OSCs). However, in the layer-by-layer processed OSCs (LbL-OSCs), polymer donors and small molecule acceptors (SMAs) are separately deposited, and it is challenging to realize a fibril network of pure SMAs with the absence of tight interchain entanglement as polymers. In this work, crystalline small molecule donors (SMDs), named TDZ-3TR and SeDZ-3TR, were designed and introduced into the L8-BO acceptor solution, forcing the phase separation and molecular fibrilization. SeDZ-3TR showed higher crystallinity and lower miscibility with L8-BO acceptor than TDZ-3TR, enabling more driving force to favor the phase separation and better molecular fibrilization of L8-BO. On the other hand, two donor polymers of PM6 and D18 with different fibril widths and lengths were put together to optimize the fibril network of the donor layer. The simultaneously optimization of the acceptor and donor layers resulted in a more ideal double-fibril network of the photoactive layer and an impressive power conversion efficiency (PCE) of 19.38 % in LbL-OSCs.     

A near-infrared porphyrin-based electron acceptor for non-fullerene organic solar cells

A star-shaped electron acceptor with porphyrin as core and rhodanine-benzothiadiazole as end groups linked with ethynyl units was developed for non-fullerene solar cells, in which a PCE of 1.9% with broad photo response was achieved when combining with a diketopyrrolopyrrole-polymer as electron donor.     

Developing Efficient Small Molecule Acceptors with sp2-Hybridized Nitrogen at Different Positions by Density Functional Theory Calculations,Molecular Dynamics Simulations and Machine Learning

Chemical structure of small molecule acceptors determines their performance in organic solar cells. Multiscale simulations are necessary to avoid trial-and-error based design, ultimately to save time and resources. In current study, the effect of sp²-hybridized nitrogen substitution at the inner or the outmost position of central core, side chain, and terminal group of small molecule acceptors is investigated using multiscale computational modelling. Quantum chemical analysis is used to study the electronic behavior. Nitrogen substitution at end-capping has significantly decreased the electron-reorganization energy. No big change is observed in transfer integral and excited state behavior. However, nitrogen substitution at terminal group position is good way to improve electron-mobility. Power conversion efficiency (PCE) of newly designed acceptors is predicted using machine learning. Molecular dynamics simulations are also performed to explore the dynamics of acceptor and their blends with PBDB-T polymer donor. Florgy-Huggins parameter is calculated to study the mixing of designed small molecule acceptors with PBDB-T. Radial distribution function has indicated that PBDB-T has a closer packing with N3 and N4. From all analysis, it is found that nitrogen substitution at end-capping group is a better strategy to design efficient small molecule acceptors.