苯并[1,2-b:4,5-b′]二噻吩的共轭聚合物光伏材料的能隙的理论研究(英文)

Theoretical studies on optical and electronic properties of conjugated polymer photovoltaic materials based on Benzo[1,2-b:4,5-b′]dithiophene

共轭聚合物材料的吸收谱带和能隙是影响太阳能电池(PSCs)能量转换效率(PCE)的主要因索,为了预测吸收谱带和能隙提高新型共轭聚合物的光伏性能,用量子化学方法计算了具有不同共轭单体的苯并[1,2-b:4,5-b′]二噻吩(BDT)的吸收光谱和能隙。基态分子结构优化用密度泛函理论(DFT)B3LYP方法及6-31G(d)基组,吸收光谱和最低激发能(E_g)用含时密度泛函理论(TD-DFT)计算。聚合物的△_(H-L)和E_G值用外推法计算,而且提出了相关参数用以调控共轭聚合物能隙和吸收谱带。计算结果与实验结果相符。

Since the absorption band and band gap of conjugated polymer donor materials are the major factors to affect the power conversion efficieny（PCE） of polymer solar cells（PSCs）,in order to predict absorption band and band gap for guiding the synthesis of novel materials with broader absorption band and smaller band gap for improving the photovoltaic properties of the conjugated polymers,quantum-chemical techniques were applied to calculate the absorption spectra and band gaps of benzo[1,2-b：4,5-b＇]dithiophene（BDT） with different conjugated units.The ground-state（So） structures of the molecules studied here were optimized using the Kohn-Sham density functional theory（DFT） with 6-31G~＊ basis set and the Becke three parameter hybrid exchange-correlation functional known as B3LYP.The ability of applied time-dependent density functional theory（TD-DFT） to predict the near-infrared absorption spectrum and excitation energy（E_g） of benzo[1,2-b：4,5-b＇]dithiophene（BDT）.Δ_（H-L）and E_g values of each polymer are obtained by extrapolating those of the oligomers to the inverse chain length equal to zero（1/n=0）.The calculated results in polymer are in good agreement with experiment results,and the results provide some useful references to control band gap and absorption band of conjugated polymers.