CdS/CuInS₂ Quantum Dots Cosensitized Solar Cells Using Functionalized Polyurethane Gel Electrolytes

Functionalized thermoplast polyurethane has been synthesised and further developed as polymer gel electrolyte for quantum dots sensitized solar cells. ¹H NMR, FTIR, and UV–vis spectroscopic technique are used to confirm the functionalization. The CdS and CuInS₂ quantum dots are used to develop the cosensitized photonaode and subsequently used to fabricate photovoltaic devices. The SILAR cycle were used to developed CdS quantum dots on TiO₂ nano-crystalline semiconductors photoanode followed by CuInS₂ quantum dots deposited through spin coating technique. The cosenitized photoanode (TiO₂/CdS/CuInS₂) has higher light harvesting efficiency as compared to single loaded quantum dots (TiO₂/CdS or TiO₂/CuInS₂ photoanode). The energy levels of the highest occupied molecular orbital, lowest unoccupied molecular orbital, valence band, and conduction band for polymer and quantum dots have been estimated through cyclic voltammetry and optical band gap calculated through UV–vis measurements and consequently match the energy levels to optimise the suitable possible combination of materials for devices fabrication. The TiO₂/CdS/CuInS₂ photoanode with developed polymer gel electrolyte shows high power conversion efficiency ⁓ 1.05%, which is almost 42% greater than that of photoanode without CuInS₂.