聚合物太阳电池光伏材料

聚合物太阳电池由共轭聚合物给体和可溶性富勒烯衍生物受体的共混膜夹在ITO透光电极和金属电极之间所组成,具有结构简单、成本低、重量轻和可制成柔性器件等突出优点,近年来受到广泛关注。聚合物太阳电池中的给体和受体光伏材料是决定器件性能的关键。本文综述了共轭聚合物给体和富勒烯受体光伏材料的最新研究进展,对共轭聚合物受体材料和给体-受体双缆型共轭聚合物光伏材料的研究进展也进行了简要介绍。在共轭聚合物给体材料中对聚噻吩衍生物以及含有苯并噻二唑的窄带隙D-A共聚物进行了重点介绍。     

基于噻咯的聚合物给体光伏材料

聚合物太阳能电池由于具有结构简单、成本低、重量轻和可制成柔性器件等突出优点,近几年受到了越来越多的关注。但是,与传统的无机硅系太阳能电池相比,较低的能量转换效率一直是制约其发展的瓶颈。近年来大量的研究显示,噻咯结构单元被引入给-受体(D-A)型共轭聚合物光伏材料中,能有效地改善相应聚合物的结晶性能,并调节其能级结构(HOMO/LUMO),从而显著改善聚合物的光伏性能。本文综述了含有噻咯环的低能隙共轭聚合物给体光伏材料的研究进展,重点介绍了含有二噻吩并噻咯单元的窄带隙D-A共轭聚合物的最新研究,并进一步提出了给体材料的研究方向以及有待解决的问题。     

苯并噻二唑单元在聚合物光伏材料设计中的应用

聚合物太阳能电池因其易于加工、可制备成柔性器件、材料来源广泛等优点得到材料界和能源界的广泛关注。有机太阳能电池效率的不断提高主要得益于材料的发展和电池器件结构的优化。从材料设计角度考虑,种类众多的给体和受体单元被开发用来构建有机共轭分子,其中,苯并噻二唑单元由于共轭平面较大和吸电子性较强的特性被广泛用于构建高性能的有机太阳能电池材料。基于此,本文首先介绍了苯并二噻吩单元及其衍生物常见的合成方法,随后总结了其在构建聚合物给体方面的应用,最后对其后续发展方向和前景提出了展望。     

非富勒烯聚合物太阳电池研究进展

综述了以p-型共轭聚合物为给体、n-型有机半导体为受体的非富勒烯聚合物太阳电池光伏材料最新研究进展,包括n-型共轭聚合物和可溶液加工小分子n-型有机半导体(n-OS)受体光伏材料,以及与之匹配的p-型共轭聚合物给体光伏材料.介绍的n-型共轭聚合物受体光伏材料包括基于苝酰亚胺(BDI)、萘酰亚胺(NDI)以及新型硼氮键连受体单元的D-A共聚物受体光伏材料,目前基于聚合物给体(J51)和聚合物受体(N2200)的全聚合物太阳电池的能量转换效率最高达到8.26%.n-OS小分子受体光伏材料包括基于BDI和NDI单元的有机分子、基于稠环中心给体单元的A-D-A型窄带隙有机小分子受体材料等.给体光伏材料包括基于齐聚噻吩和苯并二噻吩(BDT)给体单元的D-A共聚物,重点介绍与窄带隙A-D-A结构小分子受体吸收互补的、基于噻吩取代BDT单元的中间带隙二维共轭聚合物给体光伏材料.使用中间带隙的p-型共轭聚合物为给体、窄带隙A-D-A结构有机小分子为受体的非富勒烯聚合物太阳电池能量转换效率已经突破12%,展示了光明的前景.最后对非富勒烯聚合物太阳电池将来的发展进行了展望.     

高效率窄带隙聚合物太阳能电池材料

太阳能电池能够将太阳能直接转化为电能,是利用太阳能资源的一种非常有效的手段。聚合物太阳能电池因成本低、重量轻、制备方便和可制成柔性器件的优点,已经成为该领域的研究热点之一。基于窄带隙共轭聚合物给体/富勒烯受体复合材料体系制得的太阳能电池的最高转换效率已经达到8.3%,而寻找性能更优异的聚合物给体材料是进一步提高光伏性能的关键因素。本文综述了近几年关于高效率窄带隙聚合物太阳能电池给体材料的研究进展,着重介绍了苯并噻二唑类共聚物、稠环噻吩类共聚物和吡嗪类共聚物等窄带隙聚合物给体材料体系及相应光伏器件的性能,分析了各种材料的优点和不足,并对今后这一领域的发展做了展望。     

聚合物太阳能光伏技术研究进展

聚合物太阳电池因其结构简单、成本低、重量轻和可制成柔性器件等突出优点,近年来受到广泛关注,成为发展绿色可再生能源的重要方向。聚合物太阳电池中的给体和受体光伏材料是决定器件性能的关键,本文综述了共轭聚合物给体和富勒烯受体光伏材料的最新研究进展,并在共轭聚合物给体材料中对聚噻吩衍生物以及窄带隙D-A共聚物进行了重点介绍。同时讨论了薄膜优化和器件稳定性,最后从提高电池效率的几个方面展望了聚合物太阳电池的发展方向。     

基于萘二酰亚胺受体单元的n-型聚合物受体材料在光电领域的研究进展

近年来,n-型聚合物受体材料逐步在有机光电器件领域,尤其是全聚物太阳能电池领域,得到了广泛的研究。目前,报道较多的具有高的电荷迁移率和电子亲合性的n-型聚合物主要是基于萘二酰亚胺(NDI)的n-型聚合物受体材料,这类基于NDI的n-型聚合物材料表现出比富勒烯衍生物受体材料更好的热/机械性能及太阳光吸收,同时可以灵活的调节包括光学性能、电子结构、结晶性、溶解性和电荷传输等不同的内在特性从而提高器件的性能。本文根据聚合物结构组成的不同,归纳了近年来基于萘二酰亚胺的D-A聚合物受体材料的研究进展,详细描述了其相对应的给体材料和器件结构及后处理条件对器件性能的影响。同时,总结评述了针对基于萘二酰亚胺的D-A聚合物作为受体材料的全聚物太阳能电池器件工艺条件,最后展望了基于萘二酰亚胺的D-A聚合物应用在全聚物太阳能电池领域的发展前景。     

基于1,2,4-三氮唑衍生物的共轭聚合物的合成及其光伏性能

以缺电子的1,2,4-三氮唑衍生物作为拉电子结构单元(A), 以富电子的噻吩或苯并二噻吩衍生物作为推电子结构单元(D), 通过Stille偶联聚合的方法, 合成了三种主链型D-A(推-拉电子结构)的交替共聚物PT-TZ, PB-TZ和PB-TTZT. 不同富电子结构单元可使其聚合物表现出不同的光物理性能和光伏性能. 嵌入较多的噻吩单元, 可有效增大聚合物主链的共轭长度, 拓宽其吸收光谱, 因此, 聚合物PB-TTZT的光伏性能明显优于另外两种聚合物. 以三种聚合物分别作为给体材料, 以PC₆₁BM作为受体材料, 制备了聚合物太阳能电池(PSCs), 其中, 基于PB-TTZT的PSCs器件在AM 1.5 G模拟太阳光条件下的光电转换效率为1.18%.     

基于苯并二噻吩的D-A型窄带隙共轭聚合物在太阳能电池中的应用

近年来为获得有机聚合物太阳能电池更高的能量转换效率,越来越多的活性层材料被设计合成出来,尤其是给体材料。其中,基于给体单元苯并二噻吩(BDT)的D-A型窄带隙共轭聚合物更是多次刷新了有机聚合物太阳能电池效率的最高记录,目前达10.6%。本文探讨了基于苯并二噻吩的D-A型窄带隙共轭聚合物材料结构及其应用在太阳能电池中的性能参数关系,从提高开路电压、短路电流和填充因子三个方面总结出了提高基于BDT共轭聚合物太阳能电池能量转换效率的方法。     

高性能聚合物光伏材料的设计与应用

高性能聚合物光伏材料对于推动聚合物太阳能电池领域的发展具有十分重要的作用.随着研究的深入,聚合物光伏材料从早期的聚噻吩体系逐步发展到具有推拉电子作用的给体-受体(D-A)交替共聚物,其相应的器件光伏效率也从最初的1%左右提升到如今超过11%.近十年来,种类繁多的给受体单元被开发并应用于聚合物材料的构建中,其中基于苯并二噻吩(BDT)单元的聚合物材料因为具有良好的光伏性能,得到了十分广泛的应用.近年来,非富勒烯受体的迅速发展给聚合物太阳能电池的研究注入了新的活力,BDT类聚合物在基于非富勒烯受体的聚合物太阳能电池中也展现出重要的作用,已经获得了超过11%的光电转化效率.本文简要介绍了我们在高性能聚合物光伏材料的设计与应用中的相关工作,主要分为聚噻吩和苯并二噻吩材料的设计与应用、活性层形貌调控以及非富勒烯聚合物太阳能电池的相关研究.     

Effect of furan π-bridge on the photovoltaic performance of D-A copolymers based on bi(alkylthio-thienyl)benzodithiophene and fluorobenzotriazole

The medium band gap donor-acceptor(D-A) copolymer J61 based on bi(alkylthio-thienyl)benzodithiophene as donor unit and fluorobenzotriazole as acceptor unit and thiophene as π-bridge has demonstrated excellent photovoltaic performance as donor material in nonfullerene polymer solar cells(PSCs) with narrow bandgap n-type organic semiconductor ITIC as acceptor.For studying the effect of π-bridges on the photovoltaic performance of the D-A copolymers,here we synthesized a new D-A copolymer J61-F based on the same donor and acceptor units as J61 but with furan π-bridges instead of thiophene.J61-F possesses a deeper the highest occupied molecular orbital(HOMO) level at-5.45 eV in comparison with that(-5.32 eV) of J61.The non-fullerene PSCs based on J61-F:ITIC exhibited a maximum power conversion efficiency(PCE) of 8.24%with a higher open-circuit voltage(V_(oc)) of 0.95 V,which is benefitted from the lower-lying HOMO energy level of J61-F donor material.The results indicate that main chain engineering by changing π-bridges is another effective way to tune the electronic energy levels of the conjugated D-A copolymers for the application as donor materials in non-fullerene PSCs.     

Alkoxy substituted benzodithiophene-alt-fluorobenzotriazole copolymer as donor in non-fullerene polymer solar cells

A new benzodithiophene(BDT)-alt-fluorobenzotriazole(FBTA) D-A copolymer J40 was designed and synthesized by introducing 2-octyldodecyloxy side chains on its BDT units, for expanding the family of the BDT- alt-FBTA-based copolymers and investigating the side chain effect on the photovoltaic performance of the polymer in non-fullerene polymer solar cells(PSCs).J40 exhibits complementary absorption spectra and matched electronic energy levels with the n-type organic semiconductor(n-OS)(3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-sindaceno[1,2-b:5,6-b′]dithiophene)(ITIC) acceptor, and was used as polymer donor in the non-fullerene PSCs with ITIC as acceptor. The power conversion efficiency(PCE) of the PSCs based on J40:ITIC(1:1, w/w) with thermal annealing at 120 °C for 10 min reached 6.48% with a higher open-circuit voltage(Voc) of 0.89 V. The high Voc of the PSCs is benefitted from the lower-lying highest occupied molecular orbital(HOMO) energy level of J40. Although the photovoltaic performance of the polymer J40 with alkoxy side chain is lower than that of J60 and J61 with alkylthio-thienyl conjugated side chains, the PCE of6.48% for the J40-based device is still a relatively higher photovoltaic efficiency in the non-fullerene PSCs reported so far. The results indicate that the family of the BDT-alt-FBTA-based D-A copolymers are high performance polymer donor materials for non-fullerene PSCs and the side chain engineering plays an important role in the design of high performance polymer donors in the non-fullerene PSCs.     

Fluorobenzotriazole-Based Medium-Bandgap Conjugated D–A Copolymers for Applications to Fullerene-Based and Nonfullerene Polymer Solar Cells

Two new medium-bandgap (MBG) donor–acceptor (D–A) conjugated polymers (PSTF and PDTS) with fluorobenzotriazole as an A unit and spiro[cyclopenta[1,2-b:5,4-b′]dithiophene-4,9′-fluorene] (STF) or dithienosilole (DTS) as the D unit are designed and synthesized as donor materials for polymer solar cell (PSC) applications. PSTF shows a broader absorption spectrum relative to PDTS reflecting an additional high-energy absorption band due to the conjugated thiophene side chains on STF moiety. Compared with PDTS, PSTF exhibits weaker π–π aggregation and lower lying HOMO level. Photovoltaic properties of the PSCs reveal that either PSTF or PDTS using PC₆₁BM as acceptor exhibits better performances than that of ITIC as acceptor, which results from the simultaneously increased V_oc, J_sc, and FF of PC₆₁BM-based PSCs. Moreover, when combined with PC₆₁BM and ITIC, the PSTF-based PSCs exhibit an efficiency of 3.66% and 2.42%, respectively, which is 45% and almost 1.5 times higher than that of the PDTS-based PSCs, respectively. This can be ascribed to the obviously improved V_oc and FF of PSTF-based PSCs benefitted from the deeper HOMO level and better active layer morphology. Our work demonstrates that using spiro-annulated building block as donor unit to construct MBG D-A copolymers is an alternative and effective approach for achieving efficient donor materials in PSCs. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2330–2343     

Conjugated Random Terpolymer Donors towards High‐Efficiency Polymer Solar Cells

Over the past decades, polymer solar cells (PSCs) which contain conjugated polymers as electron donor and/or acceptor materials in active layers have achieved the power conversion efficiency (PCE) over 17%. Among them, tremendous alternative donor‐acceptor (D‐A) type conjugated copolymers have been reported as donor materials. Nevertheless, plenty of rooms still exist to further improve the photovoltaic performance for practical applications. Besides the exploration of the increasingly challenging novel D and/or A monomers to construct new D‐A copolymer donors, conjugated random terpolymer donors which involve a third existing monomer (D or A) provide an extra simple promising strategy to promote the photovoltaic performance to a higher level. Herein, recent progress on random terpolymer donors for efficient PSCs was reviewed. Firstly, random terpolymer donors were classified by several typical molecular building blocks. Then, the influences of the third monomer on various random terpolymers were highlighted according to the enhancement of light‐harvesting ability, modification of energy levels and optimization of the bulk‐heterojunction (BHJ) morphology. Finally, several issues which might be concerned in future research on random terpolymer donors were proposed. This review may be helpful for providing guidelines to design efficient random terpolymer donors as well as better‐understanding of the structure‐property‐performance correlations towards high performance PSCs via random terpolymer approach.     

Toward High Performance Ambipolar Transport from Super-exchange Perspective: Theoretical Insights for IID-based Copolymers

High-performance ambipolar charge transport materials can reduce the manufacturing cost of OFET and OPV devices, and simplify circuit design and device structure. In order to obtain ambipolar donor-acceptor (D-A) polymer, many efforts have been made through different donor and acceptor combination, halogenation or heteroatom substitution. However, the influencing factor for charge transport polarity is still much complicated. Based on intra-chain super-exchange mechanism for D-A polymer, we found that the energy alignment of donor and acceptor moiety has large impact on charge transport polarity. When the HOMO-LUMO (H-L) gap of the acceptor moiety is narrow, its HOMO/LUMO energy level both lie between the HOMO and LUMO of the donor moiety (sandwich-type energy alignment), and the corresponding D-A copolymers will be more likely ambipolar transport. And thus, take a narrow H-L gap thiazoleisoindigo (TzIID) acceptor as an example, we demonstrated that a series of TzIID based copolymers combined with wide H-L gap donor moieties can reveal ambipolar transport. We further predict several high performance ambipolar D-A copolymers (TzIID-TT etc.) with balanced electron and hole transport, whose effective mass (m_e*=0.146 and m_h*=0.128) is one of the smallest effective masses among ambipolar materials.

     

Fullerene derivative acceptors for high performance polymer solar cells

Polymer solar cells (PSCs) are composed of a blend film of a conjugated polymer donor and a soluble fullerene derivative acceptor sandwiched between a PEDOT?:?PSS coated ITO positive electrode and a low workfunction metal negative electrode. The conjugated polymer donor and the fullerene derivative acceptor are the key photovoltaic materials for high performance PSCs. For the acceptors, although [6,6]-phenyl-C(61)-butyric acid methyl ester (PC(60)BM) and its corresponding C(70) derivative PC(70)BM are dominantly used as the acceptors in PSC at present, several series of new fullerene derivatives with higher-lying LUMO energy level and better solubility were reported in recent years for further improving the power conversion efficiency of the PSCs. In this perspective paper, we reviewed the recent research progress on the new fullerene derivative acceptors, including various PC(60)BM-like C(60) derivatives, PC(60)BM bisadduct, PC(70)BM bisadduct, indene-C(60) bisadduct and indene-C(70) bisadduct, trimetallic nitride endohedral fullerenes and other C(60) derivatives with multi side chains. The synthesis and physicochemical properties of PC(60)BM and PC(70)BM were also introduced considering the importance of the two fullerene acceptors.     

Non-equivalent D-A copolymerization strategy towards highly efficient polymer donor for polymer solar cells

D-A copolymerization is a broadly utilized molecular design strategy to construct high efficiency photovoltaic materials for polymer solar cells (PSCs),and all the D-A copolymer donors reported till now are the alternate D-A copolymers with equal D-and A-units.Here,we first propose a non-equivalent D-A copolymerization strategy with unequal D-and A-units,and develop three novel non-equivalent D-A copolymer donors (PM6-D1,PM6-D2 and PM6-D3 with D/A unit ratio of 1.1:0.9,1.2:0.8 and1.3:0.7,respectively) by inserting more D units into the alternate D-A copolymer PM6 backbone to finely tune the physicochemical and photovoltaic properties of the polymers.The three non-equivalent D-A copolymers show the down-shifted highest occupied molecular orbital (HOMO) energy levels,higher hole mobility,higher degree of molecular self-assembly and higher molecular crystallinity with the increase of D-unit ratio in comparison with the alternate D-A copolymer PM6.As a result,all the three non-equivalent D-A copolymer-based PSCs with Y6 as acceptor achieve improved power conversion efficiency (PCE)with higher V_(oc),larger J_(sc)and higher FF simultaneously.Particularly,the PM6-D1:Y6 based PSC achieved a high PCE of17.71%,which is significantly higher than that (15.82%) of the PM6:Y6 based PSC and is one of the highest performances in the binary PSCs.     

Synthesis,characterization, thermal, and optical properties of conjugated copolymers derived from phenanthrene-9,10-dione- and dibenzo[f,h]quinoxaline

Donor–acceptor (D-A) conjugated polymers bearing phenanthrene-9,10-dione and dibenzo[f,h]quinoxaline as the acceptor units were synthesized via an optimized Suzuki cross-coupling reaction. Each of the aforementioned acceptors was reacted with three different donor comonomers, namely, fluorene, carbazole, and silafluorene derivatives, bearing long alkyl chains. The resulting copolymers display excellent solubility in common organic solvents with high chemical stability, allowing for the determination of their structural, thermal, and optical properties by various analytical techniques.