Photochemical Deposition of Semiconductor Thin Films and Their Application for Solar Cells and Gas Sensors

The photochemical deposition (PCD) technique was applied for solar cells and gas sensors. CdS and $Cd1−xZnxS$ were deposited by PCD. Thiosulfate ions $S2O32−$ act as a reductant and a sulfur source. The SnS absorption layer was deposited by three‐step pulse electrochemical deposition. For the CdS/SnS structure, the best cell showed an efficiency of about 0.2%, while for the $Cd1−xZnxS/SnS$ structure, an efficiency of up to 0.7% was obtained. For the gas sensor application, $SnO2$ was deposited by PCD from a solution containing $SnSO4$ and $HNO3.$ To enhance the sensitivity to hydrogen, Pd was doped by the photochemical doping method. The current increased by a factor of $104$ upon exposure to 5000 ppm hydrogen within 1 min at room temperature. $103$ times conductivity increase was observed even for 50 ppm hydrogen.