Dopant-free, hole-transporting polymers containing benzotriazole acceptor unit for perovskite solar cells

Dopant-free, electron donor (D)-acceptor (A) type, polymeric hole-transporting materials (HTMs) possess excellent film formability and hole transport properties, which ensure high efficiency, stability, and reproducibility to the PVSCs. Compared with benzothiadiazole (BT), benzotriazole (BTA) was less incorporated into polymeric HTMs. Herein, two indacenodithieno[3,2-b]thiophene (IDTT)-BTA copolymers BT-T and BT-TT containing different pi -bridge of thiophene and thienothiophene, are synthesized and studied. BT-T bearing thiophene pi -bridge presents decent coplanarity, higher hole mobility, and better interface morphology than its sister polymer BT-TT. The PVSC with dopant-free BT-T displayed a peak power conversion efficiency (PCE) of 17.1% and remained above 85% of its initial PCE for more than 30 days at ambient conditions. In view of the rare report on the BTA-based polymeric HTMs, this work will cast lights on further exploration of high-efficiency D-A polymeric HTMs.

Automated summary

Dopant-free, electron donor-acceptor type polymeric hole-transporting materials (HTMs) exhibit excellent properties and high efficiency and stability. This study synthesized and explored two copolymers with different pi-bridges, demonstrating good coplanarity, high hole mobility, and superior interface morphology. The dopant-free polymer exhibited significant power conversion efficiency and remained stable for an extended period at ambient conditions.