Organic bulk heterojunction solar cells based on solution processable small molecules (A–π–A) featuring 2-(4-nitrophenyl) acrylonitrile acceptors and phthalimide-based π-linkers
作者:G. D. Sharma、J. A. Mikroyannidis、Rajnish Kurchania、K. R. Justin Thomas
DOI:10.1039/c2jm16915k
日期:——
A novel small molecule-based organic donor SM [(2Z,2â²Z)-3,3â²-(((1E,1â²E)-(2-cyclohexyl-1,3-dioxoisoindoline-4,7-diyl)bis(ethene-2,1-diyl))bis(4,1-phenylene))bis(2-(4-nitrophenyl)-acrylonitrile)] featuring 2-(4-nitrophenyl)acrylonitrile as the acceptor and a Ï-conjugation bridge composed of phthalimide and styryl units, with an AâÏâA type structure, has been synthesized. It showed a long wavelength absorption band having an absorption maximum around 635 nm and the optical bandgap was 1.63 eV, which is lower than most reported conjugated polymers, including poly(3-hexylthiophene) (P3HT). The photovoltaic properties were investigated by constructing bulk heterojunction organic solar cell devices using SM as the electron donor and fullerene derivatives, i.e. PC60BM and PC70BM as the electron acceptors with the device architecture ITO/PEDOT:PSS/SM:PC60BM or PC70BM/Al. The effect of the SM/fullerene derivative weight ratio and the processing solvent were carefully investigated to improve the performance of the organic solar cells. The optimized organic solar cell with SM:PC60BM and SM:PC70BM cast from THF solvent, at a weight ratio of 1â:â3 showed power conversion efficiencies (PCEs) of about 1.70% and 2.56%, respectively. The enhanced value of PCE for the BHJ photovoltaic device based on PC70BM is related to the better absorption of PC70BM in the visible region compared to that of PC60BM. The SM:PC70BM blends cast from a DIOâTHF mixture and subsequent thermal annealing exhibited improved PCEs of 3.68% and 4.14%, respectively.
一种新型小分子有机供体SM [(2Z,2'Z)-3,3'((1E,1'E)-(2-环己基-1,3-二氧异吲哚啉-4,7-二基)双(亚乙基-2,1-二基))双(4,1-苯ylene))双(2-(4-硝基苯基)-丙烯腈)]已经合成,其中2-(4-硝基苯基)丙烯腈作为受体,phthalimide和styryl单元组成的π-共轭桥接,结构类型为A-π-A型。它显示出一个长波长吸收带,吸收最大值约为635纳米,光学带隙为1.63电子伏特,这比大多数报道的共轭聚合物要小,包括聚(3-己基噻吩)(P3HT)。通过使用SM作为电子供体,富勒烯衍生物,即PC60BM和PC70BM作为电子受体,构建了体异质结有机太阳能电池器件,其结构为ITO/PEDOT:PSS/SM:PC60BM或PC70BM/Al。仔细研究了SM/富勒烯衍生物重量比和处理溶剂对提高有机太阳能电池性能的影响。最佳的有机太阳能电池以THF溶剂铸造的SM:PC60BM和SM:PC70BM,在重量比为1:3时,功率转换效率(PCEs)分别为约1.70%和2.56%。基于PC70BM的BHJ光伏器件的PCE增强值与PC70BM在可见区域比PC60BM更好的吸收有关。从DIO-THF混合物铸造的SM:PC70BM混合物,并在随后进行了热退火,显示出了改善的PCEs分别为3.68%和4.14%。