Plant-Derived l-Theanine for Ultraviolet/Ozone Resistant Perovskite Photovoltaics

As the efficiency of perovskite solar cell has skyrocketed to as high as 25.7%, their stability has become the biggest obstacle to commercialization. Preliminary analyses suggest that additive engineering may be effective in improving both solar cell efficiency and its stability. Herein, the plant-derived natural green additive of l-Theanine (Thea) is selected to improve the crystal quality of the perovskite absorber and obtain high-performance perovskite solar cells (PSCs) with ultraviolet/ozone (UV/O-3) resistance. The characterization results reveal that the C(sic)O group in Thea can effectively inhibit the precipitation of metal Pb-0, passivate undercoordinated Pb2+ ions, and promote the nucleation and crystallization of perovskite. In addition, the combination of the N-H group and I- in the form of a hydrogen bond cooperatively reduce the probability of nonradiative recombination of photogenerated carriers and effectively improves the extraction ability of carriers from perovskite absorber. With the cooperation of C(sic)O and -NH2 groups in Thea, the champion efficiency is improved from 22.29% in the control device to 24.58%. More importantly, Thea significantly alleviates the perovskite phase transition and film decomposition induced by UV/O-3 treatment. The study provides exploratory research for the application of plant-derived green additives in the UV/O-3 resistance field of perovskite photovoltaics.

Automated summary

This study introduces the use of a plant-derived natural green additive, l-Theanine, to improve the crystal quality and stability of perovskite solar cells. The additive was found to inhibit metal precipitation, passivate ions, and enhance nucleation and crystallization of the perovskite absorber. The efficiency of the solar cells was improved, and the additive also alleviated phase transition and film decomposition induced by UV/O-3 treatment.