Modifying Surface Termination by Bidentate Chelating Strategy Enables 13.77% Efficient Kesterite Solar Cells

Abstract

Surfaces display discontinuities in the kesterite‐based polycrystalline films can produce large defect densities, including strained and dangling bonds. These physical defects tend to introduce electronic defects and surface states, which can greatly promote nonradiative recombination of electron‐hole pairs and damage device performance. Here, an effective chelation strategy is reported to suppress these harmful physical defects related to unterminated Cu, Zn, and Sn sites by modifying the surface of Cu2ZnSn(S,Se)4 (CZTSSe) films with sodium diethyldithiocarbamate (NaDDTC). The conjoint theoretical calculations and experimental results reveal that the NaDDTC molecules can be coordinate to surface metal sites of CZTSSe films via robust bidentate chelating interactions, effectively reducing surface undercoordinated defects and passivating the electron trap states. Consequently, the solar cell efficiency of the NaDDTC‐treated device is increased to as high as 13.77% under 100 mWcm−2 illumination, with significant improvement in fill factor (FF) and open‐circuit voltage (VOC). This surface chelation strategy provides strong surface termination and defect passivation for further development and application of kesterite‐based photovoltaics.This article is protected by copyright. All rights reserved

Analysis of the Optical Properties and Electronic Structure of Semiconductors of the Cu2NiXS4 (X = Si, Ge, Sn) Family as New Promising Materials for Optoelectronic Devices

“…Additionally, this allows for the kesterite film to be thinned down to a point where the solar panel's cost can be decreased without sacrificing efficiency [28]. The efficiency of kesterite-based solar cells has recently risen from 12.6% to 13.6% [29][30][31]. However, the performance of solar cells based on this material is still far from the theoretical limit, indicating that the efficiency potential of kesterite is still little exploited.…”

“…In this regard, recently the properties of kesterites have also been studied by various theoretical methods, as a result of which the efficiency of solar cells based on them is constantly increasing [25][26][27][28][29][30][31][32][33][34][35][36]. Density functional theory (DFT) is a potent theoretical approach that has gained significant traction in the last 10 years as a major tool for the theoretical study of solid materials.…”