Long‐term stability of dye‐sensitised solar cells

Abstract

AbstractAccelerated ageing tests on large numbers of nanocrystalline dye‐sensitised solar cells (nc‐DSC) show that, to first order, separation between the effects of the stresses of visible light soaking, UV illumination and thermal treatment on long‐term stability is possible. The corresponding mechanisms are electrochemical, photochemical and purely chemical in nature. It was found that visible light soaking alone is not a dominant stress factor. A dramatic improvement in UV stability has been achieved by using MgI2 as additive to the electrolyte. Thermal stress appears to be one of the most critical factors determining the long‐term stability of nc‐DSC and is strongly related to the chemical composition of electrolyte solvents and additives. Encouraging stability results have been obtained for cells based on pure nitrile‐based solvents: (1) A minor decrease in performance of initially 5.5% solar efficient cells has been found after 2000 h at 60°C without light soaking; (2) After 900 h ageing at 85°C, a decrease of 30% in maximum power has been observed; (3) After 3400 h of combined thermal stress and continuous light soaking (45°C, 1 sun equivalent) good stability with 15% decrease in maximum power can be demonstrated. It should be noted that such good thermal stability has not been reported previously for dye‐sensitised solar cells so far. Copyright © 2001 John Wiley & Sons, Ltd.