Spectroelectrochemical evidence for the effect of phase structure and interface on charge behavior in poly(3-hexylthiophene): Fullerene active layer

•The steady-state absorption spectra of P3HT+, P3HT−, PCBM+ and PCBM− were obtained.•The effect of morphology of active layer on charge generation was identified.•Non-equilibrium transport of electron and hole was confirmed in PSCs.

To investigate the correlation between morphology of active layer and performance of polymer solar cells (PSCs). Poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) were selected as research object and five PSCs based on active layers with varied morphology were fabricated. The results showed that P3HT crystalline phase and donor-acceptor (D-A) interface had an important influence on PSCs performance, which was revealed by structure characterization and J-V measurement. To further understanding the effect of phase structure and D-A interface on charge behavior. Spectroelectrochemistry measurement (SEC) was performed to characterize the steady-state optical absorption of P3HT, PCBM cation and anion in varied active layers, and the spectra difference of cations and anions was analyzed. The results were found that D-A interface could promote charge generation. P3HT crystalline phase and PCBM aggregation phase were beneficial for improving the charge transport ability. Meanwhile, the non-equilibrium transport of electron and hole in PSCs was corroborated by SEC.