Cation exchange synthesis of AgBiS$_2$ quantum dots for highly efficient solar cells

TL;DR

This paper introduces a novel cation exchange synthesis method for AgBiS$_2$ quantum dots, enabling efficient solar cells with simplified, room-temperature processing and high-quality nanocrystals.

Contribution

The study presents a new cation exchange approach for synthesizing AgBiS$_2$ nanocrystals at room temperature, avoiding high-temperature, vacuum-dependent methods.

Findings

Achieved power conversion efficiencies up to 7.35%.

Produced monodisperse AgBiS$_2$ nanocrystals with preserved size and shape.

Demonstrated effective incorporation of bismuth cations into Ag$_2$S nanocrystals.

Abstract

Silver bismuth sulfide (AgBiS$_2$) nanocrystals have emerged as a promising eco-friendly, low-cost solar cell absorber material. Their direct synthesis often relies on the hot-injection method, requiring the application of high temperatures and vacuum for prolonged times. Here, we demonstrate an alternative synthetic approach via a cation exchange reaction. In the first-step, bis(stearoyl)sulfide is used as an air-stable sulfur precursor for the synthesis of small, monodisperse Ag2S nanocrystals at room-temperature. In a second step, bismuth cations are incorporated into the nanocrystal lattice to form ternary AgBiS$_2$ nanocrystals, without altering their size and shape. When implemented into photovoltaic devices, AgBiS$_2$ nanocrystals obtained by cation exchange reach power conversion efficiencies of up to 7.35%, demonstrating the efficacy of the new synthetic approach for the formation of high-quality, ternary semiconducting nanocrystals.