烷基侧链长度对受体小分子的光伏性能的影响

Effect of Length of Alkyl Side Chain on Photovoltaic Performance of Small Acceptor Molecules

摘要:

以苯并二茚并二噻吩(IDT)为给体(D)单元,二氰基茚酮(IC)为受体(A)单元,合成了四个A-D-A型非富勒烯受体小分子。通过调节IDT结构单元上烷基取代基链的长度(-C₆H₁₃,-C₈H₁₇,-C₁₀H₂₁和C₁₆H₃₃),系统研究了分子热学性质、光学性质、能级结构及光伏性能随烷基链长度的变化规律。测试结果表明,烷基链长度的变化对分子的热稳定性、HOMO能级、最大吸收峰值和吸收范围并没有很大的影响,但随着烷基链变短,分子的摩尔消光系数变弱、结晶性升高。基于PBDB-T∶C₈-IDT-IC的光伏器件显示了较高的光电转换效率,达5.90%,而PBDB-T∶C₁₆-IDT-IC的器件效率最低,表明烷基取代基链长度对材料的光伏性能具有一定影响。

Abstract:

A series of non-fullerene small molecules(IDIC) based on indacenodithiophene (IDT) were synthesized, and the molecular thermal properties, optical properties, energy levels and photovoltaic properties varying with the length of alkyl chains were systematically investigated by changing the alkyl substituent (-C₆H₁₃,-C₈H₁₇,-C₁₀H₂₁ and C₁₆H₃₃) on the IDT units. The results show that the change of alkyl chain length has no significant effect on the thermal stability, HOMO energy level, wavelength of maximum absorbance and absorption range, but with the alkyl chain getting shorter, the molecular molar extinction coefficient becomes weaker and the crystallinity increases. The photovoltaic devices based on PBDB-T∶C₈-IDT-IC show the best power conversion efficiency of 5.90%, while PBDB-T∶C₁₆-IDT-IC has the lowest device efficiency, indicating that the alkyl substituent chain length has a certain effect on the photovoltaic performance of the materials.