Ceramic grains: Highly promising hole transport material for solid state QDSSC

Polysulphide has proven to be an efficient electrolyte for QDSSC, but at the cost of corroding the counter electrode and degrading the sensitizer due to its high redox potential. In this view for the first time, we have used oxide nanoceramics as low cost, easily processable and highly porous solid-state electrolytes for QDSSCs. High residual porosity and formation of liquid phase nanodomains across grain boundaries have added advantages for adsorption and diffusion in these hole transport layer. Yttria stabilized zirconia and ceria co doped yttria stabilized zirconia are the two solid state electrolytes designed in place of polysulphide. Dopants namely Y3+ and Ce4+ in ZrO2 induces defects, oxygen vacancies and band shifts resulting in good charge transport. The interfaces and charge transfer kinetics suggests, recombination resistance offered by these ceramics avoid the back electron transfers via the downward shift of valence band (VB) much closer to that of sensitizer and also act as barriers (or passivation layer) to effectively suppress electron recombinations, resulting in high stability and Voc of the device. Devices designed with these new HTLs show efficiencies on par with polysulphide; they are extremely stable for almost up to 60 days (in ambient conditions), while cells fabricated with polysulphide electrolyte tend to degrade the device within 5 days. [Display omitted] •Nanoceramics: low cost, easily processable and highly porous solid-state electrolytes for QDSSCs.•Formation of liquid phase nanodomains across grain boundaries allows better diffusion of electrolyte.•Ceramics act as barriers (or passivation layer) to suppress electron recombinations, resulting in high stability and Voc.