Liquid crystal based electrolyte with light trapping scheme for enhancing photovoltaic performance of quasi-solid-state dye-sensitized solar cells

Abstract

In this study, nematic liquid crystal, 4-Cyano-4′-n-heptyloxybiphenyl, is introduced into the poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF) based polymeric gel electrolyte for quasi-solid-state dye-sensitized solar cells (DSC), aiming to improve the photovoltaic performance of DSC. The effects of liquid crystal on the electrochemical behavior of I 3 −/ I − and photovoltaic performance, dynamic response as well as long-term stability of DSC are studied in detail. It is found that although the addition of liquid crystal would hinder the charge transport in the electrolyte, it could still fulfill the requirements of the photocurrent for DSC. More important, a significant increase in the photocurrent density for DSC is observed when liquid crystal is introduced into PVDF based polymeric gel electrolyte, resulting in the higher photoelectric conversion efficiency. The large increase in short-circuit photocurrent density could be attributed to the higher light harvesting efficiency, which is caused by the effective formation of light trapping scheme in electrolyte due to the addition of liquid crystal. Besides, at-rest long-term stability shows that when liquid crystal is introduced into PVDF based polymeric gel electrolyte, DSC could retain over 92% of its initial photoelectric conversion efficiency value after 1000 h, exhibiting relatively better stability.