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

Abstract

carbon emission energy is an urgent issue for all countries in the century. Solar energy is the cleanest, safest, and most reliable energy in cognition. Perovskite photovoltaic technology has become a rising candidate in the photovoltaic field with its rapidly improved efficiency, simple preparation process, and low cost.Perovskite-based photovoltaic devices with great operation performance are inseparable from perovskite absorber materials with excellent performance, including a wide tolerance factor and adjustable optical band gap. [1][2][3][4][5] Currently, organic-inorganic hybrid perovskite solar cells (PSCs) have been reported to have a certified power conversion efficiency (PCE) of up to 25.7%. [6] However, because of the hybrid combination of organic and inorganic, there are weak van der Waals forces, [7] sufficient ion migration space, and loose ion bonds in the coordination of perovskite structure. These factors will lead to the abnormal distortion of perovskite lattice and even the change of components, resulting in various defects, such as Pb and I vacancies, and PbI mutual antisite substitution. [8][9][10] These defects act as carrier traps around the grain boundary and surface of perovskite films, play the part of nonradiative recombination centers, quench photogenerated carriers, and 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O group in Thea can effectively inhibit the precipitation of metal Pb 0 , passivate undercoordinated Pb 2+ 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O and NH 2 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.

Manipulating Electron Density Distribution of Nicotinamide Derivatives Toward Defect Passivation In Perovskite Solar Cells

“…It is further confirmed that CNA is more conducive to reducing nonradiative recombination, which also contributes to increase open circuit voltage ( V OC ). [ 46 ]…”

“…It is further confirmed that CNA is more conducive to reducing nonradiative recombination, which also contributes to increase open circuit voltage (V OC ). [46] The matching arrangement of energy levels at the perovskite/HTL interface is crucial for photogenerated carrier transport and eventually collection by the electrode. On account of the relative arrangement of energy levels, the charge transport process at the perovskite/HTL interface is further analyzed on the basis of the Schottky-Mott limit.…”

Magic guanidinium cations in perovskite solar cells: from bulk to interface

“…68,69 Other distinctive functions are presented in the promotion of uniform and compact perovskite films by modulating the crystallization process such as nucleation and growth, and bandgap alignment through self-doping effect. 70,71 In most cases, the hydrophobic nature of the molecules also improves the ambient stability of the devices. GABr and GASCN are typically used as additives.…”

Dual‐Interface Modulation with Covalent Organic Framework Enables Efficient and Durable Perovskite Solar Cells

“…Semiconducting perovskites share a general chemical component of APbX 3 (A = Cs, FA, MA, or mixed‐halide; X = Cl, Br, I, or mixed‐halide) and crystal structure with corner‐shared [PbX 6 ] 4− octahedra. [ 13,14 ] There are weak van der Waals forces and loose ionic bonding within the perovskite crystal structure, which leads to abnormal distortion of the perovskite lattice and even component separation under operating conditions such as humidity, heat, and illumination exposure, [ 15–17 ] resulting in a large number of defects around the grain boundaries and top and bottom surfaces of the perovskite film, such as Pb, I vacancies and Pb─I antisites. [ 10,18,19 ] These unfavorable trap states, further acting as recombination centers, lead to severe nonradiative recombination, photogenerated carrier annihilation, and intrinsic degradation of perovskite materials.…”

“…Since the first report of organic-inorganic hybrid lead halide perovskite solar cells (PSCs) by Miyasaka et al in 2009, [1] it has exposure, [15][16][17] resulting in a large number of defects around the grain boundaries and top and bottom surfaces of the perovskite film, such as Pb, I vacancies and Pb─I antisites. [10,18,19] These unfavorable trap states, further acting as recombination centers, lead to severe nonradiative recombination, photogenerated carrier annihilation, and intrinsic degradation of perovskite materials.…”