Efficient and Stable Perovskite Solar Cells Achieved by Using Bifunctional Interfacial Materials to Modify SnO2 and MAPbI3-xClx Simultaneously

As an effective electron transport layer, tin oxide (SnO2) has attracted much attention owing to its charge mobility and chemical stability, but it still suffers from high trap at the SnO2/perovskite interface. Herein, a simple interface treatment strategy of diethylenetriaminepentakis (methylphosphonic acid) (DETAPMP) to effectively passivate the SnO2 /MAPbI(3-x)Cl(x) interface is reported. Under the optimal DETAPMP concentration, the average power conversion efficiency (PCE) of MAPbI(3-x)Cl(x) solar cells is improved from 17.27 to 19.41% and the champion device shows a PCE of 20.02%. In the (FAPbI(3))(0.9.5) (MAPbBr(3))(0.0.5) system, the average PCE can be improved from 20.08 to 20.95% and the champion device shows a PCE of 21.65%. Such an enhancement is mainly attributed to two factors: (1) the phosphate group in DETAPMP reacts with SnO to passivate SnO2 defects and (2) the ammonium group in DETAPMP is expected to balance the PbI3- charge and passivate PbI3- defects, thus achieving lower charge recombination and better carrier transport. In addition, due to the hydrophobicity of DETAPMP and the reduced grain boundaries in the perovskite film, the long-term stability of the perovskite with DETAPMP-modified SnO2 is improved under the ambient conditions with 20-30% humidity.

Automated summary

A simple interface treatment strategy using DETAPMP successfully passivated the SnO2/MAPbI(3-x)Cl(x) interface, leading to improved efficiency and long-term stability of perovskite solar cells.