Keywords: conversion efficiency, dye–sensitised solar cells, DSSC, nanoparticles, renewable energy, titanium dioxide, TiO2, nanotechnology, commercialisation, solar energy, solar power
Dye–sensitised solar cells using TiO2 nanoparticles: a review
Over the past two decades, several research papers have been published on dye–sensitised solar cells ever since its conception was first reported in 1991. This paper discusses their basic principle, fabrication in the laboratory and developments, based on results reported in literature. The various factors which stand in favour and against their commercialisation and their characterisation by techniques such as scanning electron microscopy, X–ray diffraction and energy dispersive analysis have also been discussed. DSSC consists of a porous–structured nanocrystalline semiconductor coating electrode. Adsorbed dye molecules act as the photosensitised anode while a platinised fluorine–doped tin oxide (FTO) glass acts as the counter electrode. An electrolyte acts as a conductor to electrically connect the two electrodes. The sensitising dye in a DSSC is anchored to a wide–bandgap semiconductor such as TiO2, SnO2 or ZnO. When the dye absorbs light, the photoexcited electron rapidly transfers to the conduction band of the semiconductor, which carries the electron to one of the electrodes. A redox couple, usually comprised of iodide/triiodide (I–/I3–), then reduces the oxidised dye back to its neutral state and transports the positive charge to the platinised counter–electrode.