Effect of the self-assembled gel network formed from a low molecular mass organogelator on the electron kinetics in quasi-solid-state dye-sensitized solar cells

Abstract

A low molecular mass organogelator (LMOG), N , N ¢ -1,5-pentanediylbis-dodecanamide, was applied to quasi-solid-state dye-sensitized solar cells (QS-DSSCs). The crosslinked gel network was self-assemblied by the LOMG in the liquid electrolyte, and the in situ assembly process of gelator can be obtained by the polarized optical microscopy (POM). On one hand, the network hinders the diffusion of redox species and accelerates the electron recombination at the interface of the TiO2 photoanode/electrolyte. On the other hand, Li+ can interact with the amide carbonyl groups of the gelators and the adsorption of Li+ onto the TiO2 surface decreases, leading to a negative shift of the TiO2 conduction band edge, accelerated electron transport and decreased electron injection efficiency ( η inj) of QS-DSSC. As a result, the incidental photon-to-electron conversion efficiency (IPCE), the short circuit photocurrent density ( J sc) and the open circuit voltage ( V oc) of the QS-DSSC are decreased compared with those of the liquid electrolyte based DSSC (L-DSSC), which indicates that the electron recombination plays a great role in the photovoltaic performances of DSSC. Remarkably, the QS-DSSC exhibits excellent thermal and light-soaking stabilities during accelerated aging tests for 1000 h, which is attributed to a great intrinsic stability of the gel electrolyte with a high gel to solution transition temperature ( T gel = 108°C).