Kinetically controlled crystallization via plant-derived additives boosts the efficiency of carbon-based perovskite solar cells exceeding 20%

Abstract

Effectively controlling crystallization kinetics to obtain high-quality perovskite films with large grains and low defect density is a key strategy for fabricating high-performance hole transport layer-free carbon-based perovskite solar cells (C-PSCs). Herein, a natural plant-derived molecule, locust bean gum (LBG), was introduced into the precursor solution to regulate the crystallization process of perovskites. The addition of LBG more effectively promotes the transformation of PbI2 into PbI3− complexes as prenucleation clusters to accelerate the nucleation process. Meanwhile, the growth rate of perovskite grains during annealing is significantly slowed down due to the stronger interaction between the precursor material and LBG. Benefiting from such rapid nucleation and slow crystallization, high-quality perovskite films with larger crystal sizes and optimized energy level arrangements have been formed. Consequently, the optimized C-PSC achieved a maximum power conversion efficiency of 20.23%, surpassing the efficiency of 18.22% for control devices. Additionally, the long-term stability testing demonstrates excellent storage stability and enhanced light stability under illumination. These findings provide new insights into the potential of natural plant-derived additives for achieving higher-performance perovskite photovoltaic devices.