Stable Performance of Chemically Deposited Antimony Sulfide-Lead Sulfide Thin Film Solar Cells under Concentrated Sunlight

Abstract

Thin film solar cells of FTO/CdS/Sb2S3/C-Ag or FTO/CdS/Sb2S3/PbS/C-Ag prepared via chemical deposition of thin films of CdS (100 nm), Sb2S3 (200 - 400 nm) and PbS (110 or 220 nm) on transparent conductive oxide of SnO2:F (FTO) are presented. These cells are stable under concentrated sunlight of intensity of up to 10 kW/m2. The optical bandgap of Sb2S3 thin films is 1.57-1.83 eV and of the PbS thin film, 1.03-1.40 eV. The photoconductivity of Sb2S3 is 5.8 × 10−7 Ω−1 cm−1(n-type); of PbS thin films it is 10−2 Ω−1 cm−1 (p-type); and of CdS film it is 2 × 10−3 Ω−1 cm−1. The addition of PbS thin film in the cells notably improves the open circuit voltage (Voc), short circuit current (Jsc) as well as the energy conversion efficiency (η) of these cells. Under sunlight, Voc is 438 mV, Jsc is 1.38 mA/cm2 and η is 0.12% for a FTO/CdS/Sb2S3(400 nm)/C-Ag cell; and 578 mV, 8.61 mA/cm2 and 1.34%, for a FTO/CdS/Sb2S3(400 nm)/PbS(220 nm)/C-Ag cell. Under 4 kW/m2, Voc is 581 mV, Jsc is 3.55 mA/cm2 and η is 0.10% for the FTO/CdS/Sb2S3(400 nm)/C-Ag cell; and 611 mV, 23.54 mA/cm2 and 0.89%, respectively, for the FTO/CdS/Sb2S3 (400 nm)/PbS(220 nm)/C-Ag cell. Through the measurement methodology described for evaluating the performance of the cells, we establish that these cells remain stable under concentrated as well as steady-state solar radiation.