Antimony Chalcogenide/Lead Selenide Thin Film Solar Cell with 2.5% Conversion Efficiency Prepared by Chemical Deposition

Abstract

Antimony sulfide-selenide solid solutions offer optical band gaps, Eg, in the 1–1.88 eV interval; and lead selenide offers Eg upward of its bulk value, 0.28 eV, depending on the extent of quantum confinement. In this work, thin film solar cells of SnO2:F/CdS/Sb2(Se/S)3/PbSe/C-Ag are developed by chemical deposition of the thin films on transparent conductive oxide (TCO) glass. To prepare the solar cell, first a CdS thin film of 100 nm in thickness is deposited on the TCO from a solution containing Cd(II)-citrate complex. On this, a thin film is deposited from a solution containing potassium-antimony tartrate, thioacetamide and selenosulfate, which upon heating at 280°C in nitrogen ambient results in a Sb2S1.2Se1.8 film of 150 nm in thickness with an Eg of 1.67 eV. PbSe thin film 110 nm in thickness is deposited on it from a solution of Pb-citrate complex and selenosulfate, with crystalline grain diameter 10 nm, and Eg of 1.86 eV. The cell shows open circuit voltage (Voc), 454 mV, short circuit current density (Jsc) 12.5 mA/cm2, fill factor (FF) 0.44 and conversion efficiency (η) 2.5%. The observed cell parameters are backed by a tentative energy level diagram and an estimate for the light generated current density.