Selenium cooperated polysulfide electrolyte for efficiency enhancement of quantum dot-sensitized solar cells

Abstract

Abstract The modification of polysulfide electrolyte with additives has been demonstrated as an effective way to improve the photovoltaic performance of quantum dot-sensitized solar cells (QDSCs). Most of these additives can inhibit the charge recombination processes at photoanode/electrolyte interface and favor the improvement of Voc of cell devices. Herein, we showed that the incorporation of elemental selenium (Se) in polysulfide electrolyte to form polyselenosulfide species can notably improve the performance of QDSCs. Unlike previous reports, we present here an integrated investigation of the effects of polyselenosulfide species in polysulfide electrolyte on the photovoltaic performance of QDSCs from both of the photoanode and counter electrode (CE) aspects. Electrochemical impedance spectroscopy (IS) and open-circuit voltage-decay (OCVD) measurements demonstrated that the introduction of Se into polysulfide electrolyte can not only retard charge recombination at photoanode/electrolyte interface, but also reduce the charge transfer resistance at CE/electrolyte interface, resulting in the improvement of Jsc and FF values. Consequently, the average efficiency of Zn − Cu − In − Se QDSCs was improved from 9.26% to 9.78% under AM 1.5 G full one sun illumination.