Enhanced charge carrier extraction and transport with interface modification for efficient tin-based perovskite solar cells

Tin-based perovskites have become the most promising non-lead perovskites due to their ideal band gap and low toxicity. Although the open circuit voltage of tin-based perovskite solar cells (TPSCs) continues to approach the theoretical value, the short-circuit current is still far from the theoretical value. Here, we describe an interface modification method by regulating the property of hole transport layer, PEDOT: PSS, which improves the surface molecular morphology and improves the energy level alignment of PEDOT: PSS/perovskite interface. Advanced GIWAXSand IR-SNOM characterization are conducted to achieve multi-dimensional characterization ofnanoscale surface morphology and chemical distribution of PEDOT: PSS. With the multi-attributeoptimization, charge carrier extraction and non-radiative recombination are also improved. Theresultant TPSCs exhibit a higher power conversion efficiency of 13.32% in compared with the control device of 10.50%, accompanied with an increase in the short-circuit current from 18.10 to 20.50 mA cm-2 and FF from 68.23% to 76.43%. This work demonstrates a reliable strategy for improving charge carrier extraction and device performance for lead-free TPSCs.