Ag–In–Zn–S quantum dots for hybrid organic–inorganic solar cells

Abstract

Quantum dots of (AgIn)xZn2(1−x)S2 (x = 0.6, 0.8, and 1.0) capped by oleylamine were prepared and applied for hybrid organic–inorganic solar cells consisting of glass–indium–tin-oxide/ZnO/(AgIn)xZn2(1−x)S2/poly(3-hexylthiophene)/MoO3/Ag. The short-circuit current density (Jsc) and open-circuit voltage (Voc) of the hybrid solar cells were measured, and we found a low power conversion efficiency (PCE) below 0.1%. From the incident photon-to-current efficiency (IPCE) profiles of the hybrid devices, there is no marked photocurrent generation from 350 to 700 nm, which is ascribed to the absorption region of (AgIn)xZn2(1−x)S2. To improve the photovoltaic performance, ligand substitution from oleylamine to pyridine was performed. The PCE of the hybrid cell using the pyridine-capped (AgIn)xZn2(1−x)S2 was improved twofold in terms of both Jsc and Voc as compared with that of the oleylamine-capped one. In particular, from the IPCE measurements, a remarkable (more than doubled) enhancement of photocurrent generation from 400 to 450 nm was observed with the pyridine-substituted nanoparticles.