N-Aryl stilbazolium dyes as sensitizers for solar cells

Abstract

Given the urgent need to develop clean and renewable energy sources, there is much current interest in using molecular dyes, especially transition metal complexes, as sensitizers in solar energy harvesting [1]. Traditional solar cells rely on the direct absorption of photons by a semiconductor, but their efficiency is limited because visible light absorption requires narrow band-gap semiconductors which are inherently unstable with respect to photodegradation. In a major breakthrough in 1991, O’Regan and Grätzel reported efficient photosensitization of a wide band-gap semiconductor by a trinuclear RuII-2,2-bipyridyl-based dye [2]. The chromophoric properties of such complexes derive from intense, low energy metal-to-ligand charge-transfer transitions.