Synthesis and characterization of benzodithiophene–isoindigo polymers for solar cells
作者:Zaifei Ma、Ergang Wang、Markus E. Jarvid、Patrik Henriksson、Olle Inganäs、Fengling Zhang、Mats R. Andersson
DOI:10.1039/c1jm14940g
日期:——
Three new alternating polymers with the electron-deficient isoindigo group as the acceptor unit and benzo[1,2-b:4,5-bâ²]dithiophene (BDT) or BDT flanked by thiophenes (or octylthiophenes) as the donor unit were designed and synthesized. All the polymers have good thermal stability, solubility and broad absorption spectra. Their photophysical, electrochemical and photovoltaic (PV) properties were investigated. To understand their different PV performance in the resulting polymer solar cells (PSCs), the morphology of their blends with fullerene derivatives was investigated by atomic force microscopy, and the molecular geometries as well as the molecular frontier orbitals were simulated by density functional theory calculations (Gaussian 09). The polymer PBDT-TIT, with BDT flanked by thiophenes as the donor unit and isoindigo as the acceptor unit, exhibits quite planar backbones and its blend with fullerene derivatives shows optimal morphology. As a result, the PSCs based on PBDT-TIT with a conventional device configuration of ITO/PEDOT:PSS/PBDT-TIT:PC61BM/LiF/Al showed a power conversion efficiency of 4.22%, with a short-circuit current density of 7.87 mA cmâ2, an open-circuit voltage of 0.79 V and a fill factor of 0.68 under the AM 1.5G illumination with an intensity of 100 mW cmâ2 from a solar simulator.
三种新型交替聚合物以缺电子异靛基作为受体单元,苯并[1,2-b:4,5-b-]二噻吩(BDT)或侧翼为噻吩(或辛基噻吩)的BDT作为供体单元设计并合成。所有聚合物都具有良好的热稳定性、溶解性和宽的吸收光谱。研究了它们的光物理、电化学和光伏(PV)特性。为了了解它们在所得聚合物太阳能电池(PSC)中的不同光伏性能,通过原子力显微镜研究了它们与富勒烯衍生物的共混物的形态,并通过密度泛函理论计算模拟了分子几何形状以及分子前沿轨道(高斯 09)。聚合物PBDT-TIT以BDT为侧翼的噻吩作为供体单元,异靛蓝作为受体单元,表现出相当平面的主链,并且其与富勒烯衍生物的共混物显示出最佳的形态。结果,基于PBDT-TIT且传统器件配置为ITO/PEDOT:PSS/PBDT-TIT:PC61BM/LiF/Al的PSC的功率转换效率为4.22%,短路电流密度为7.87 mA cm-2,在来自太阳模拟器的 AM 1.5G 照明、强度为 100 mW cm-2 下,开路电压为 0.79 V,填充因子为 0.68。