有机太阳能电池性能衰减机理研究进展

近年来随着非富勒烯Y系列明星分子受体的出现, 单结有机太阳能电池的光电转换效率已经突破19%, 但是器件在运行条件下缺乏良好的稳定性, 严重制约了其商业化发展. 因此越来越多的研究聚焦于造成有机太阳能电池性能衰减的原因以及如何提高有机太阳能电池的稳定性. 由于有机太阳能电池复杂的器件结构、不尽相同的活性层材料以及在稳定性研究中条件的差异, 造成了对有机太阳能电池器件衰减研究的困难. 为了更全面地了解有机太阳能电池的衰减过程, 对近些年有机太阳能电池器件衰减过程的研究成果进行综述, 总结了由于给受体材料化学分解、活性层形貌变化、传输层和电极腐蚀以及界面反应等原因造成的器件性能衰减, 并介绍了近些年关于提高器件稳定性的一些策略, 最后对有机太阳能电池的未来发展进行了展望.     

十年磨一剑：专访非富勒烯受体的先驱者占肖卫教授

<正>自从1995年首次报道本体异质结有机太阳能电池以来,在近二十年时间里,富勒烯衍生物已成为最广泛使用的电子受体,非富勒烯受体的器件效率远远低于富勒烯衍生物。而富勒烯太阳光吸收弱、能级调控难、生产成本高、形貌稳定性差的缺点,限制了有机太阳能电池领域的可持续发展。2015年以来,非富勒烯受体领域不断取得突破,器件效率从低于7%快速提升到高于17%,并大大超过富勒烯受体,使人们看到了有机太阳能电池的巨大潜力,吸引了国际学术界越来越多的研究力量投入到非富勒烯     

稠环电子受体光伏材料

基于非富勒烯受体的有机太阳能电池是化学和材料领域的热点前沿之一,中国领跑这个热点前沿.中国学者在非富勒烯受体材料方面取得了一系列重要的创新成果.我们提出了"稠环电子受体(FREA)"这一新概念,构建了高性能稠环电子受体新体系,发明了明星分子ITIC.我们的原创性工作引起了国内外同行的广泛关注和跟进.目前,基于稠环电子受体的有机太阳能电池效率已达到13%~14%,超过富勒烯体系.ITIC等稠环电子受体的出现颠覆了富勒烯受体在有机太阳能电池领域的统治地位,开创了有机太阳能电池的非富勒烯时代.本文简要评述了我们在高性能稠环电子受体设计与器件应用中的研究进展,并展望稠环电子受体的未来发展.     

基于非共价相互作用的非富勒烯受体光伏材料研究进展

有机太阳能电池由于制备简单、成本低,而且易于制备大面积柔性电池,因而受到了研究人员的广泛关注.非富勒烯受体材料因具有合成相对简单、易于纯化、能级和带隙可调等优点,极大地促进了有机太阳能电池效率的提高.基于非富勒烯受体材料的太阳能电池已经成为目前有机太阳能电池的研究热点之一,而具有分子内非共价键相互作用的受体材料是非富勒烯受体体系的重要组成部分.通过引入O、F、N、Se等杂原子,形成分子内非共价键相互作用,可以有效提高非富勒烯受体材料的平面性和电荷迁移率,降低光学带隙并拓宽吸收光谱,从而进一步提高太阳能电池的光伏性能.本文介绍了近几年来基于分子内非共价键相互作用的聚合物和小分子非富勒烯受体材料的研究进展,并展望了其发展趋势和应用前景.     

基于非富勒烯电子受体的半透明有机太阳能电池

半透明有机太阳能电池以其独特的光电特性在建筑集成光伏上具有广阔的应用前景。非富勒烯小分子受体近几年发展十分迅速。其中,基于非富勒烯小分子受体的半透明有机太阳能电池具有较高的光电转换效率和平均可见光透过率,因而得到了广泛关注。本文总结了近几年来非富勒烯受体型半透明有机太阳能电池的最新研究进展,探究活性层材料设计及器件构型优化对半透明有机太阳能电池的影响,希望为半透明有机太阳能电池在今后研究中新材料体系的优选提供一定的参考。     

基于卟啉小分子给体与双组分富勒烯受体的高效三元有机太阳能电池（英文）

最近,有机太阳能电池中三元策略的出现使得高能量转化效率和简便的器件制备方式有望同时实现.大量实验证明,通过构造三元有机太阳能电池可以实现吸光互补以提高电流或者在能级间形成级联以提高开压.设计并合成了以并噻吩取代卟啉为核,通过炔键连接二酮吡咯并吡咯末端基团的新分子,命名为DEP-TT,该分子有较小的能带间隙(1.31 eV),光谱吸收可达898 nm.以该卟啉分子为给体,富勒烯PC71BM为受体制备双组分有机太阳能电池,效率可达7.46%,但开压相对较低(0.75 V).进一步研究发现,加入10%的富勒烯衍生物ICBA制备三元有机太阳能电池,效率可增大至8.15%,这是基于卟啉小分子为给体的有机太阳能电池取得相对较高效率的器件之一.由于PCBM和ICBA两组分间形成级联能级和协同作用,器件效率明显提高,这意味着三元有机太阳能电池的构建可以同时提高开压和电流,从而实现器件效率的全面提高.     

石墨烯在有机/聚合物太阳能电池中的应用进展

近年来有机/聚合物太阳能电池得到国内外研究者的广泛关注,但其目前较低的能量转换效率有待进一步提高以满足市场化的需求。本文综述了新型二维电子材料石墨烯及其衍生物在有机/聚合物太阳能电池的受体材料、电极材料、电荷传输材料方面的研究进展,分析了石墨烯功能化的方法以及石墨烯衍生物应用于有机太阳能电池中的性能参数,最后对石墨烯及其衍生物的合成和修饰方法进行展望,以期将来在有机太阳能电池材料中得到更好的应用。     

基于聚合物给体与非富勒烯有机小分子受体材料的有机太阳能电池研究进展

在本体异质结有机太阳能电池的研究中,富勒烯及其衍生物是一类重要的n-型电子受体材料,然而基于富勒烯的材料有一些难以克服的弱点,例如在可见光范围内较弱且窄的吸收、很难调节的带隙、溶解性较差等,这些都严重限制了富勒烯类材料在有机太阳能电池中作为n-型受体材料更广泛的应用。而非富勒烯n-型电子受体材料比富勒烯类材料拥有在可见光光谱中更加宽广的吸收范围、能级更易调节、合成简便、加工成本更低、溶解性能更加优异等重要特点,目前基于非富勒烯类材料的本体异质结有机太阳能电池的能量转换效率超过了4%。本文综述了几类非富勒烯类有机小分子受体材料的研究进展,讨论了提高基于非富勒烯类有机小分子材料的有机太阳能电池器件性能的关键因素,并对其发展前景作了展望。     

理性调控聚合物给体-非富勒烯受体的混溶性制备高效率有机太阳能电池※

除了非富勒烯受体的设计与合成, 聚合物给体的选择对非富勒烯太阳能电池的光伏性能同样重要. 本工作设计并合成一种共轭骨架无sp³杂化碳原子的新型非富勒受体(命名为MDB), 并将其作为模型化合物研究给受体混溶性和分子有序堆积对太阳能电池性能的影响. 本工作选择三种宽带隙聚合物给体(PM6、J71和P3HT)与MDB共混来制备太阳能电池. 得益于MDB和PM6之间适度的混溶性, 由二者组成的混合膜表现出合适的相分离, “face-on”的分子取向和更紧密有序的分子堆积, 从而促进了载流子传输, 并抑制了电荷复合. 因此基于PM6:MDB的器件实现了13.26%的优异光电转换效率, 远高于基于J71:MDB (8.16%)和P3HT:MDB (0.45%)的器件. 该工作证明了给体-受体之间合适的混溶性是实现高效率有机太阳能电池的关键因素之一, 这对有机光伏材料的设计与合成具有重要指导意义.     

Cd基化合物纳米晶-有机聚合物杂化太阳能电池研究进展

有机-无机杂化太阳能电池因其结合了有机材料和无机材料各自的优势而引起了人们的广泛关注和研究. Cd基化合物纳米晶因其具有制备方法简单、尺寸及形貌可控、载流子迁移率高和稳定性好等优点而成为最早被研究的一类无机受体. 本文介绍了有机-无机杂化太阳能电池的结构及原理, 分析了影响有机-无机杂化太阳能电池效率的三个主要因素, 分别是开路电压(V_oc)、短路电流(J_sc)和填充因子(FF). 从改善Cd基化合物纳米晶的合成方法, 增加Cd基化合物纳米晶和有机聚合物间的界面接触, 以及优化Cd基化合物纳米晶和有机聚合物所用溶剂和所占比例等方面阐述了近年来Cd基化合物纳米晶-有机聚合物杂化太阳能电池的研究进展. 并展望了Cd基化合物纳米晶-有机聚合物杂化太阳能电池的发展方向.     

Ternary solvent-processed efficient organic solar cells based on a new A-DA'D-A acceptor derivative employing the 3rd-position branching side chains on pyrroles

Recent advances in non-fullerene acceptors(NFAs),typically Y6,have driven power conversion efficiency(PCE) of single-junction orga nic solar cells(OSCs) over 16%.Mea nwhile,it becomes essential to know how to adopt simple strategies to further improve device performance.In this work,a new A-DA'D-A acceptor derivative,Y19-N3 employing 3-ethylheptyl branched at the 3^rd-position instead of 2-ethylhexyl on the pyrroles of Y19 is reported.The selection of an appropriate solvent in casting device is implemented to maximize the photovoltaic performance.PBDB-T:Y19-N3-based OSCs treated with a ternary solvent of CF/CB(1:3,v/v) and 0.8% DIO exhibit the optimal PCE of 13.77% here,with the significantly improved V_oc(0.78 V) and FF(0.72) as well as the high J_sc(24.46 mA/cm²).Further characterizations indicate that this ternary solvent-treated PBDB-T/Y19-N3 film exhibits the more appropriate morphological features with the highly efficient charge generation and collection as well as the more balanced electron and hole mobilities.This work combines molecular design and device engineering to improve the photovoltaic properties,which is important to the development of OSCs.     

Fluorinated Photovoltaic Materials for High‐Performance Organic Solar Cells

Over the past decade, organic solar cells (OSCs) have achieved a dramatic boost in their power conversion efficiencies from about 6 % to over 16 %. In addition to developments in device engineering, innovative photovoltaic materials, especially fluorinated donors and acceptors, have become the dominant factor for improved device performance. This minireview highlights fluorinated photovoltaic materials that enable efficient OSCs. Impressive OSCs have been obtained by developing some important molds of fluorinated donor and acceptor systems. The molecular design strategy and the matching principle of fluorinated donors and acceptors in OSCs are discussed. Finally, a concise summary and outlook are presented for advances in fluorinated materials to realize the practical application of OSCs.     

Small molecule organic semiconductors on the move: promises for future solar energy technology

This article is written from an organic chemist's point of view and provides an up-to-date review about organic solar cells based on small molecules or oligomers as absorbers and in detail deals with devices that incorporate planar-heterojunctions (PHJ) and bulk heterojunctions (BHJ) between a donor (p-type semiconductor) and an acceptor (n-type semiconductor) material. The article pays particular attention to the design and development of molecular materials and their performance in corresponding devices. In recent years, a substantial amount of both, academic and industrial research, has been directed towards organic solar cells, in an effort to develop new materials and to improve their tunability, processability, power conversion efficiency, and stability. On the eve of commercialization of organic solar cells, this review provides an overview over efficiencies attained with small molecules/oligomers in OSCs and reflects materials and device concepts developed over the last decade. Approaches to enhancing the efficiency of organic solar cells are analyzed.     

Altering alkyl-chains branching positions for boosting the performance of small-molecule acceptors for highly efficient nonfullerene organic solar cells

The emergence of the latest generation of small-molecule acceptor(SMA) materials,with Y6 as a typical example,accounts for the surge in device performance for organic solar cells(OSCs).This study proposes two new acceptors named Y6-C2 and Y6-C3,from judicious alteration of alkyl-chains branching positions away from the Y6 backbone.Compared to the Y6,the Y6-C2 exhibits similar optical and electrochemical properties,but better molecular packing and enhanced crystallinity.In contrast,the Y6-C3 shows a significant blue-shift absorption in the solid state relative to the Y6 and Y6-C2.The as-cast PM6:Y6-C2-based OSC yields a higher power conversion efficiency(PCE) of 15.89% than those based on the Y6(15.24%) and Y6-C3(13.76%),representing the highest known value for as-cast nonfullerene OSCs.Prominently,the Y6-C2 displays a good compatibility with the PC_(71)BM.Therefore,a ternary OSC device based on PM6:Y6-C2:PC_(71)BM(1.0:1.0:0.2) was produced,and it exhibits an outstanding PCE of 17.06% and an impressive fill factor(FF) of 0.772.Our results improve understanding of the structureproperty relationship for state-of-the-art SMAs and demonstrate that modulating the structure of SMAs via fine-tuning of alkylchains branching positions is an effective method to enhance their performance.     

Single-wall carbon nanotube-containing cathode interfacial materials for high performance organic solar cells

Water/alcohol soluble cathode interfacial materials(CIMs)are playing important roles in optoelectronic devices such as organic light emitting diodes,perovskite solar cells and organic solar cells(OSCs).Herein,n-doped solution-processable single-wall carbon nanotubes(SWCNTs)-containing CIMs for OSCs are developed by dispersing SWCNTs to the typical CIMs perylene diimide(PDI)derivatives PDIN and PDINO.The Raman and X-ray photoelectron spectroscopy(XPS)measurement results illustrate the ndoped behavior of SWCNTs by PDIN/PDINO in the blend CIMs.The blended and n-doped SWCNTs can tune the work function and enhance the conductivity of the PDI-derivative/SWCNT(PDI-CNT)composite CIMs,and the composite CIMs can regulate and down-shift the work function of cathode,reduce the charge recombination,improve the charge extraction rate and enhance photovoltaic performance of the OSCs.High power conversion efficiency(PCE)of 17.1%and 17.7%are obtained for the OSCs based on PM6:Y6 and ternary PM6:Y6:PC₇₁ BM respectively with the PDI-CNTcomposites CIMs.These results indicate that the ndoped SWCNT-containing composites,like other n-doped nanomaterials such as zero dimensional fullerenes and two dimensional graphenes,are excellent CIMs for OSCs and could find potential applications in other optoelectronic devices.     

Facile,Versatile and Stepwise Synthesis of High-Performance Oligomer Acceptors for Stable Organic Solar Cells

Oligomer acceptors have recently emerged as promising photovoltaic materials for achieving high power conversion efficiency (PCE) and long-term stability in organic solar cells (OSCs). However, the limited availability of diverse acceptors, resulting from the sole synthetic approach, has hindered their potential for future industrialization. In this study, we present a facile and effective stepwise approach that utilizes two consecutive Stille coupling reactions for the synthesis of oligomer acceptors. To demonstrate the feasibility of the novel approach, we successfully synthesize a trimer acceptor, Tri-Y6-OD, and further systematically investigate the impact of oligomerization on device performance and stability. The results reveal that this approach has significant advantages compared to the conventional method, including reduced formation of unwanted by-products and lower difficulties in purification. Remarkably, the OSC based on PM6 : Tri-Y6-OD achieves an impressive PCE of 18.03 % and maintains 80 % of the initial PCE (T₈₀) for 1523 h under illumination, surpassing the performance of the corresponding small molecule acceptor Y6-OD-based device. Furthermore, the versatility of the synthetic strategy in obtaining diverse acceptors is further demonstrated. Overall, our findings provide a facile, versatile and stepwise way for synthesizing oligomer acceptors, thereby facilitating the development of stable and efficient OSCs.     

Non-fullerene acceptor fibrils enable efficient ternary organic solar cells with 16.6% efficiency

Optimizing the components and morphology within the photoactive layer of organic solar cells(OSCs) can significantly enhance their power conversion efficiency(PCE). A new A-D-A type non-fullerene acceptor IDMIC-4F is designed and synthesized in this work, and is employed as the third component to prepare high performance ternary solar cells. IDMIC-4F can form fibrils after solution casting, and the presence of this fibrillar structure in the PBDB-T-2F:BTP-4F host confines the growth of donors and acceptors into fine domains, as well as acting as transport channels to enhance electron mobility. Single junction ternary devices incorporating 10 wt% IDMIC-4F exhibit enhanced light absorption and balanced carrier mobility, and achieve a maximum PCE of 16.6% compared to 15.7% for the binary device, which is a remarkable efficiency for OSCs reported in literature. This non-fullerene acceptor fibril network strategy is a promising method to improve the photovoltaic performance of ternary OSCs.     

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...     

Recent Progress in Organic Solar Cells: A Review on Materials from Acceptor to Donor

In the last few decades, organic solar cells (OSCs) have drawn broad interest owing to their advantages such as being low cost, flexible, semitransparent, non-toxic, and ideal for roll-to-roll large-scale processing. Significant advances have been made in the field of OSCs containing high-performance active layer materials, electrodes, and interlayers, as well as novel device structures. Particularly, the innovation of active layer materials, including novel acceptors and donors, has contributed significantly to the power conversion efficiency (PCE) improvement in OSCs. In this review, high-performance acceptors, containing fullerene derivatives, small molecular, and polymeric non-fullerene acceptors (NFAs), are discussed in detail. Meanwhile, highly efficient donor materials designed for fullerene- and NFA-based OSCs are also presented. Additionally, motivated by the incessant developments of donor and acceptor materials, recent advances in the field of ternary and tandem OSCs are reviewed as well.     

Improving open-circuit voltage by a chlorinated polymer donor endows binary organic solar cells efficiencies over 17%

Power conversion efficiency(PCE) of single-junction polymer solar cells(PSCs) has made a remarkable breakthrough recently.Plenty of work was reported to achieve PCEs higher than 16% derived from the PM6:Y6 binary system.To further increase the PCEs of binary OSCs incorporating small molecular acceptor(SMA) Y6,we substituted PM6 with PM7 due to the deeper highest occupied molecular orbital(HOMO) of PM7.Consequently,the PM7:Y6 has achieved PCEs as high as 17.0% by the hotcast method,due to the improved open-circuit voltage(V_(OC)).Compared with PM6,the lower HOMO of PM7 increases the gap between E_(LUMO-donor) and E_(HOMO-acceptor),which is proportional to V_(OC).This research provides a high PCE for single-junction binary PSCs,which is meaningful for device fabrication related to PM7 and commercialization of PSCs.