Higher open-circuit voltage set by cobalt redox shuttle in SnO2 nanofibers-sensitized CdTe quantum dot solar cells

Abstract

In this study, we report an efficient CdTe-SnO2 quantum dot (QD) solar cell fabricated by heat-assisted drop-casting of hydrothermally synthesized CdTe QDs on electrospun SnO2 nanofibers. The as-prepared QDs and SnO2 nanofibers were characterized by dynamic light scattering (DLS), UV–Vis spectroscopy, photoluminescence (PL) spectra, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The SnO2 nanofibers deposited on fluorine-doped tin oxide (SnO2) and sensitized with the CdTe QDs were assembled into a solar cell by sandwiching against a platinum (Pt) counter electrode in presence of cobalt electrolyte. The efficiency of cells was investigated by anchoring QDs of varying sizes on SnO2. The best photovoltaic performance of an overall power conversion efficiency of 1.10%, an open-circuit voltage (Voc) of 0.80V, and a photocurrent density (JSC) of 3.70mA/cm2 were obtained for cells with SnO2 thickness of 5–6µm and cell area of 0.25cm2 under standard 1 Sun illumination (100mW/cm2). The efficiency was investigated for the same systems under polysulfide electrolyte as well for a comparison.