Functional prototype modules of antimony sulfide selenide thin film solar cells

Abstract

Thin film solar cells of antimony sulfide selenide in the cell structures of: (i) FTO/CdS (120 nm)/Sb2S0.6Se2.4 (500 nm)/C-Ag and (ii) FTO/CdS (120 nm)/Sb2S1.4Se1.6 (500 nm)/C-Ag are found to reach solar-to-electric energy conversion efficiency (η) exceeding 5%. Here FTO was F-doped SnO2 thin films of sheet resistance 7 Ω; CdS thin films were prepared by chemical bath deposition at 80 °C from solutions of cadmium nitrate and thiourea; thin films of Sb2SxSe3-x were prepared from powder mixtures of Sb2S3 and Sb2Se3 in vacuum thermal evaporation; and CAg were colloidal graphite electrodes on which colloidal silver paint was applied and dried. The absorber layers in solar cells have optical bandgap 1.40 eV (Sb2S0.6Se2.4) – 1.43 eV (Sb2S1.4Se1.6) and photoconductivity, 10−5 Ω−1 cm−1. Averaged Solar cell parameters for (i) are: open circuit voltage (Voc), 0.476 V; short circuit current density, 21.7 mA/cm2; Fill Factor (FF), 0.50; and η, 5.16%; and for (ii) the corresponding values are: 0.500 V; 22.4 mA/cm2; 0.47; and 5.26% reporting on cell area 0.5 cm2. The best among solar cell (i) has η of 5.7% and (ii) is of 5.5%. Prototype modules consisting of seven series-connected solar cells, each of 1 cm2 in area of (ii) are: Voc, 3.2 V; short circuit current, 21.1 mA; FF, 0.39; η, 4.1% for active area (7 cm2) and power, 28.8 mW. This module is able to light-up under the sun, blue light emitting diode of 20 mW nominal power at 2.75–3.0 V. Overall prospects for further work on these solar cells are discussed.