Pyrazino[2,3-g]quinoxaline-based conjugated copolymers with indolocarbazole coplanar moieties designed for efficient photovoltaic applications
作者:Qiang Peng、Xiangju Liu、Yuancheng Qin、Jun Xu、Mingjun Li、Liming Dai
DOI:10.1039/c1jm10433k
日期:——
A series of low band gap copolymers consisting of electron-accepting pyrazino[2,3-g]quinoxaline (PQx) and an electron-donating indolo[3,2-b]carbazole and thiophene units have been designed and synthesized by Stille coupling polymerization. Their optical and electrical properties could also be facilely fine-modulated for photovoltaic application by adjusting the donor/acceptor ratios. UV-vis measurements showed that increasing the content of PQx units led to enhanced absorption. The band gaps obtained from UV-vis spectra, CV scanning, and DFT modeling all indicated a narrowing band gap with increasing the PQx content in the copolymer structure. The photovoltaic solar cells (PSCs) based on these copolymers were fabricated and tested with a structure of ITO/PEDOT:PSS/copolymer:PCBM/Ca/Al under the illumination of AM 1.5G, 100 mW cm−12. The best performance was achieved using P3/[70]PCBM blend (1 : 3) with Jsc = 9.55 mA cm−2, Voc = 0.81 V, FF = 0.42, and PCE = 3.24%, which is the highest efficiency for the PQx and indolo[3,2-b]carbazole based devices. The present results also indicate that the efficient photovoltaic materials with suitable electronic and optical properties can be achieved by just fine-tuning the ratios of the strong electron-deficient accepters and large-π planar donors.
一系列由电子接受型吡嗪并[2,3-g]喹喔啉(PQx)和电子供给型吲哚[3,2-b]咔唑及噻吩单元组成的低带隙共聚物通过Stille偶联聚合反应被设计和合成。通过调节给体/受体比例,其光学和电学性能也能方便地微调以应用于光伏领域。紫外-可见光谱测量显示,增加PQx单元的含量可增强吸收。从紫外-可见光谱、循环伏安扫描和DFT模拟获得的带隙都表明,随着共聚物结构中PQx含量的增加,带隙变窄。基于这些共聚物的光伏太阳能电池(PSCs)被制备和测试,结构为ITO/PEDOT:PSS/共聚物:PCBM/Ca/Al,在AM 1.5G、100 mW cm−2的照射下。最佳性能是通过P3/[70]PCBM混合物(1:3)实现的,Jsc = 9.55 mA cm−2,Voc = 0.81 V,FF = 0.42,PCE = 3.24%,这是PQx和indolo[3,2-b]咔唑基器件中最高的效率。目前的研究结果还表明,通过精细调节强电子缺乏受体和大π平面供体的比例,可以实现具有适当电子和光学性能的高效光伏材料。