Solar cells and prototype modules of variable bandgap antimony sulfide selenide thin films made by chemical deposition

All-chemically deposited solar cells of CdS/Sb 2 S 2.3 Se 0.7 /Sb 2 S 0.46 Se 2.54 absorber films of 5.5 – 6.0% conversion efficiency constituting prototype module CH of 21.8 mW and efficiency 4%. The modules light-up blue green LED’s of bias voltage of > 2.64 V, available from them under the sun. • Solar cell efficiency reaches 6 % (on 0.25 cm 2 ) in chemically deposited Sb-S-Se solar cells. • Their prototype PV module 5.4 cm 2 is of 20 mW at 4 % efficiency; lights up blue-green LED. • Process steps for solar cell and module production are clearly described. • Future work to improve the cell and module performance are suggested. Antimony sulfide (Sb 2 S 3 ) with a bandgap ( E g ) of 1.88 eV and antimony selenide (Sb 2 Se 3 ) with an E g , 1.1 eV, both of orthorhombic crystalline structure, can form thin films of Sb 2 S x Se 3-x of variable bandgap, 1.1 – 1.88 eV. In chemical deposition, thin films of Sb 2 S 2.3 Se 0.7 (film, C) with E g , 1.58 eV and Sb 2 S 0.46 Se 2.54 (film, H) with E g , 1.31 eV were obtained by varying the selenosulfate – to – thioacetamide (SS:TA) ratio from 0.033 (C) to 0.3 (H) in the deposition bath. Solar cell structures of fluorine-doped tin oxide (FTO)/CdS (75 – 80 nm)/Sb 2 S x Se 3-x (90 – 180 nm)/graphite were made with colloidal graphite paint applied on an area 0.25 cm 2 and heated in nitrogen (20 torr pressure) for 30 min. Silver paint was applied on the FTO around the demarked cells and on the graphite electrode. Under standard test conditions, the Sb 2 S 2.3 Se 0.7 solar cell (C) gave: V oc of 0.552 V, J sc of 8.6 mA/cm 2 , fill factor ( FF ) 0.32 and efficiency ( η ) of 1.52 %. Solar cell of Sb 2 S 0.46 Se 2.54 (H) gave: 0.427 V, J sc of 23.1 mA cm – 2 , and FF of 0.54, with η of 5.32 %. Solar cell prepared with variable bandgap C-H films improved η to 6 % with V oc of 0.461 V, and J sc of 24.73 mA cm – 2 . Prototype modules of six series connected cells of variable bandgap absorbers of Sb 2 S x Se 3-x , each of 0.9 cm 2 in area (active area, 5.4 cm 2 ), gave under standard operating condition, V oc of 2.8 V, with short circuit current ( I sc ) 17.24 mA, FF of 0.46 with η of 4 %. Variable bandgap Sb 2 S x Se 3-x prototype modules produced by chemical deposition is a viable option for their continued improvement.