Improved mobility and lifetime of carrier for highly efficient ternary polymer solar cells based on TIPS-pentacene in PTB7: PC71BM

• High PCE of 8.09% with a simultaneous enhancement of JSC and FF was achieved.
• Optical, electrical and morphological properties of ternary system were investigated.
• Incorporation of TIPS-pentacene increased the mobility and lifetime of carrier.
• Low thickness dependent TIPS-pentacene based ternary polymer solar cells was found.
• Ternary polymer solar cells based on other systems also showed improved performance.

Highly efficient ternary polymer solar cells (T-PSCs) realized by the improved mobility and lifetime of carrier in PTB7: PC71BM: TIPS-pentacene blends were fabricated. By adjusting the weight ratios of third component TIPS-pentacene in the binary PTB7: PC71BM blends, we found that the short circuit current and fill factor (FF) were simultaneously enhanced, resulting in a maximum power conversion efficiency (PCE) of 8.09% with 21.3% improvement. The improved photovoltaic performance of T-PSC was mainly due to the enhanced light absorption, energy level cascading, optimized blend morphology, and increased hole mobility. It was also found that the incorporation of TIPS-pentacene increased the average hole lifetime, ensuring efficient hole transport and collection with suppressed bimolecular recombination, contributing to the photocurrent. Additionally, the low thickness dependent row-off of FF indicates TIPS-pentacene is a promising third component for the realization of thick film T-PSC. The improved PCEs were obtained as well for other ternary donor: acceptor: TIPS-pentacene systems, demonstrating that the incorporation of TIPS-pentacene is a wide practicable methodology for the development of highly efficient T-PSCs.

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