Cation‐Disorder Engineering Promotes Efficient Charge‐Carrier Transport in AgBiS2 Nanocrystal Films

Abstract

AbstractEfficient charge‐carrier transport is critical to the success of emergent semiconductors in photovoltaic applications. So far, disorder has been considered detrimental for charge‐carrier transport, lowering mobilities, and causing fast recombination. This work demonstrates that, when properly engineered, cation disorder in a multinary chalcogenide semiconductor can considerably enhance the charge‐carrier mobility and extend the charge‐carrier lifetime. Here, the properties of AgBiS2 nanocrystals (NCs) are explored as a function of Ag and Bi cation‐ordering, which can be modified via thermal‐annealing. Local Ag‐rich and Bi‐rich domains formed during hot‐injection synthesis are transformed to induce homogeneous disorder (random Ag‐Bi distribution). Such cation‐disorder engineering results in a sixfold increase in the charge‐carrier mobility, reaching ≈2.7 cm2 V−1 s−1 in AgBiS2 NC thin films. It is further demonstrated that homogeneous cation disorder reduces charge‐carrier localization, a hallmark of charge‐carrier transport recently observed in silver‐bismuth semiconductors. This work proposes that cation‐disorder engineering flattens the disordered electronic landscape, removing tail states that would otherwise exacerbate Anderson localization of small polaronic states. Together, these findings unravel how cation‐disorder engineering in multinary semiconductors can enhance the efficiency of renewable energy applications.