Mixed Cations Polymer Gel Electrolytes for Quasi-Solid-State Dye-Sensitized Solar Cells

The electrolyte acts as a charge transport mediator between the photoanode and the counter electrode of dye-sensitized solar cells (DSSCs). However, liquid electrolyte limits the lifetime of DSSCs owing to leakage and high volatility issues. Thus, polymer gel electrolytes (PGEs) have been developed to minimize these problems. In this article, PGEs have been synthesized by employing polyvinylpyrrolidone as a host polymer and potassium iodide (KI) and ammonium iodide (NH₄I) as iodide salts. The PGE comprising of mixed salt (KI + NH₄I) shows a higher conductivity compared with PGEs with single salt at room temperature. The ionic conductivity of PGEs directly affects the efficiency of DSSCs. The solar cell assembled with mixed salt (0.02g KI + 0.05g NH₄I) PGE shows the power conversion efficiency of 0.121% superior to that of DSSCs fabricated with KI (0.061%) and NH₄I (0.068%) based PGEs separately.

I. Introduction

The demand of energy is increasing with the passage of time and most of current energy demand is fulfilled by fossil fuel based resources, which are contributing greatly in greenhouse effect. Photovoltaic (PV) solar cells directly convert solar energy into electric energy. Inorganic silicon (Si) solar cells are still dominated in the market owing to their comparatively high efficiency (14–19%) and long-term performance [1], [2]. However, rigid structure, need of exceedingly pure Si for getting high efficiency, and energy-intensive manufacturing process trigger researchers to develop alternative material for solar cells. Perovskite solar cells and dye-sensitized solar cells (DSSCs) are also part of the thin-film PV technology. Perovskite solar cells are very efficient but are unstable against humidity and oxidative environment [3], [4]. DSSCs on the other hand are easy to fabricate with relatively good power conversion efficiency. DSSCs can work even in diffused sunlight and cloudy environment, where other solar cells fail to work [5].