Non-toxic Bi2S3 quantum dot-sensitized TiO2 electrodes for cost-efficient solar power conversion

Inorganic light harvesting materials are revolutionising the current research scope of quantum dot-sensitized solar cells (QDSSCs) day by day. However, it is challenging due to the issues in toxicity and stability of existing light-harvesting materials. Herein, we present highly stable non-toxic bismuth trisulfide (Bi2S3) QDSSCs with iodide/triiodide redox electrolyte. The solar cell is configured as FTO/TiO2 P90/TiO2 P25/Bi2S3/(I-/I-3(-)) electrolyte/Pt. Bi2S3 quantum dots (QDs) were fabricated onto the FTO/TiO2 P90/TiO2 P25 electrode at room temperature using the dip-successive ionic layer adsorption reaction (Dip-SILAR), which is an easy and efficient technique. Electron microscopy confirmed that the quantum dots formed uniformly on the photoanode, with sizes ranging from 50 nm to 80 nm. QDSSCs with an active cell area of 0.16 cm(2 )were characterized under an illumination of 100 mW cm(-2) with AM 1.5 spectral filter and the results depicted that the best cell acquired a power conversion efficiency of 0.26 % with an open circuit voltage (V-oc) of 482.9 mV and short circuit current density (J(sc)) of 1.05 mA cm(-2). To enhance the stability, polyvinylpyrrolidone (PVP) based gel polymer electrolyte has been used. The high cost of conventional light harvesting materials may be significantly reduced by one-step fabrication of Bi2S3 using the SILAR technique.