Effect of interface contacts between TiO2 particles on electron transport in dye-sensitized solar cells

Abstract

Based on sol-gel and screen-printed method, nanoporous TiO2 thin films obtained under different sintering temperatures and times are adopted in dye-sensitized solar cells. According to FESEM, TiO2 particles tend to compact through touch contact under low sintering temperature, but touch contact is substituted by surface contact when the temperature is up to 510 ℃, which results in larger particle coordination number. Moreover, the influence of different contact ways between TiO2 particles on the electron transport is investigated by IMPS/IMVS technology. The results indicate that with the sintering temperature increasing from 420 ℃ to 510 ℃, the electron transport time ( d) decreases while the electron effective diffusion length (L n) increases, owing to the increased contact surface between TiO2 particles. However, when the sintering temperature increases up to 550 ℃, the porous structure of the TiO2 electrode collapses and new surface state appears on the TiO2 surface, leading to the increase of d. It is suggested that the larger short-circuit current density (Jsc) and efficiency () can be obtained when the sintering temperature of nanoporous TiO2 film is in a range of 480-510 ℃.