Synthesis of Copper Antimony Sulfide Nanocrystals based on Cu2S Nanoparticles Capped with Sb2S3 Ligand for Solar Cell Applications

Abstract

With the aim to replace the energy of fossil fuels with solar energy, researchers have focused their efforts on the development of next-generations solar cells [1]. The solar cells based on inorganic metal chalcogenides nanocrystals (NCs) are shaping up as promising candidates because of their unique optical/electrical properties and processability. Copper antimony sulfide (CAS) is I-V-VI type metal chalcogenides based on low-toxic and earth-abundant elements that can be synthesized in four main phases: CuSbS2 (chalcostibite), Cu12Sb4S13 (tetrahedrite), Cu3SbS3 (skinnerite), and Cu3SbS4 (fematinite). All four phased CAS exhibit p-type semiconducting behaviors with an optical band gap ranging from 0.5 to 2 eV and a high absorption coefficient between 104 and 105 cm-1. Despite of its attracting optical and electrical properties, CAS NCs have been rarely studied for solar cell applications achieving, up to now, a power conversion efficiency record of 0.01% [2]. One of the main drawbacks of NCs in solar cell applications is the utilization of large organic ligands required for stability. However, these organic ligands act as insulators that hinder NCs-based solar cells’ performance. In this work, we synthesized different phased CAS NCs using copper sulfide (Cu2S) NPs as precursor and the ligand exchange concept to remove the organic ligands and replace them with antimony sulfide (Sb3S2). By adjusting the ligand amount and molar concentration, we were able to control the stoichiometry leading to formation of different CAS phases. We fabricated photovoltaic devices composed of CAS NCs thin films by NCs thinning process on substrates. We will discuss the correlation between CAS properties and photovoltaic device performance.