Biopolymer passivation for high-performance perovskite solar cells by blade coating

Thin films of perovskite deposited from solution inevitably introduce large number of defects, which serve as recombination centers and are detrimental for solar cell performance. Although many small molecules and polymers have been delicately designed to migrate defects of perovskite films, exploiting credible passivation agents based on natural materials would offer an alternative approach. Here, an ecofriendly and cost-effective biomaterial, ploy-L-lysine (PLL), is identified to effectively passivate the defects of perovskite films prepared by blade-coating. It is found that incorporation of a small amount (2.5 mg mL(-1)) of PLL significantly boosts the performance of printed devices, yielding a high efficiency of 19.45% with an increase in open-circuit voltage by up to 100 mV. Density functional theory calculations combined with X-ray photoelectron spectroscopy reveal that the functional groups (-NH2, -COOH) of PLL effectively migrate the Pb-I antisite defects via Pb-N coordination and suppress the formation of metallic Pb in the blade-coated perovskite film. This work suggests a viable avenue to exploit passivation agents from natural materials for preparation of high-quality perovskite layers for optoelectronic applications. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

Thin films of perovskite deposited from solution contain defects that hinder solar cell performance, but using natural materials as passivation agents could offer a solution. Poly-L-lysine (PLL) was found to effectively passivate perovskite film defects, improving printed device performance. This work demonstrates the potential of using natural materials for preparing high-quality perovskite layers in optoelectronic applications.