4-Tert-butylpyridine-assisted low-cost and soluble copper phthalocyanine as dopant-free hole transport layer for efficient Pb-and Sn-based perovskite solar cells

The preparation of suitable hole transport material(HTM)is critical to the performance and stability of perovskite solar cells(PSCs)with low-cost.Herein,a mass producible and soluble copper phthalocyanine decorated with butoxy donor groups(CuPcOBu)was designed as HTM and prepared by a facile two-step synthetic route.To generate high quality HTM film,4-tertbutylpyridine(tBP)was doped into CuPc-OBu to prepare the film and then removed by annealing.Such a t BP-assisted strategy resulted in the best efficiency of the PSCs with lead trihalide perovskite up to 19.0%(small-area of 0.1 cm^2)and 10.1%(the active area of 8.0 cm^2 for the module device).And the best efficiency of the tin-based PSCs with CuPc-OBu reached to 6.9%.More importantly,the device with CuPc-OBu as HTM revealed the remarkably enhanced stability.This work provides a new strategy to improve the film-quality of free-doping HTMs and enhance the efficiency and stability of Pb-and Sn-based PSCs with low-cost.