Dithiocarbamate‐Based Solution Processing for Cation Disorder Engineering in AgBiS₂ Solar Absorber Thin Films

Abstract Cation disorders refer to the phenomenon where cations are randomly distributed in multi‐cation systems. These disorders have emerged as an effective strategy for tailoring material properties across diverse applications. Notably, engineering cation disorder in AgBiS₂ has garnered attention, owing to its remarkable enhancement of light absorption coefficients, which are crucial for efficient solar energy conversion in ultrathin light absorber layers. In this study, a novel dithiocarbamate (DTC)‐based solution processing method designed to control cation disorder is presented in AgBiS₂ thin films. Unlike conventional approaches that rely on heat treatment, the strategy is based on molecular coordination dynamics between DTC and metal cations. By adjusting the ratio of DTC to the metal cations, the formation of cation‐disordered AgBiS₂ thin films is demonstrated. Notably, the order‐to‐disorder transition is solely dependent on the DTC‐metal coordination and independent of the annealing temperature. These disordered films exhibit a high light absorption coefficient (>5 × 10⁵ cm⁻¹), mirroring the characteristics of thermally‐treated cation‐disordered AgBiS₂ nanocrystals reported previously. The disordered AgBiS₂ thin‐film photodetector exhibited a higher photocurrent density and responsivity compared to its ordered counterpart. The approach establishes a novel platform for cation disorder engineering, paving the way for advancements in cation‐disordered materials with diverse applications.