Improved performance and long-term stability of organogelator electrolyte based semi-solid-state dye sensitized solar cells with electrospun ZnO-TiO2 hybrid films

The liquid electrolytes for dye-sensitized solar cells (DSSCs) have been identified as one of main obstacles for commercialization. One possible way to resolve this problem is to employ the semi-solid electrolyte. In this respect, we apply two types of electrolytes, namely liquid and low molecular weight organic gelator (LMOG) to fabricate the semi-solid state DSSCs and investigate their effects over the efficiency and long-standing thermal stability of devices. Unlike the conventional TiO2 nanoparticulate films, we have introduce a hybrid oxide layer consisting of nanocomposites of TiO2 nanospheres (NSPs) mingled with ZnO nanofibers (NFs) namely (mixed ZnO NFs + TiO2 NSPs) produced by a novel electrospray technique. This route resulted in an effective contact between the electrolyte and the highly porous layer of dye-coated hybrid film as the gel electrolyte penetrated within the pores. The semi-solid state DSSCs fabricated using hybrid oxide films for the LMGO based electrolyte exhibits power conversion efficiency (PCE) of 9.51%, which is considerably greater compared to cells based on TiO2 nanoparticulate films (5.14%). The semi-solid state DSSCs using the LMOG-based gel electrolyte demonstrate the significantly improved device performance and stability compared to the devices using the liquid electrolyte owing to their enhanced light trapping which serves as a scattering layer. Remarkably, the champion devices based on gel electrolyte produce the maximum PCE of 10.69%, the highest efficiency reported so far for these types of devices.