High performance all-solid-state dye-sensitized solar cells based on cyanobiphenyl-functionalized imidazolium-type ionic crystals

Abstract

Organic ionic crystals carrying 4-cyano-4′-hydroxybiphenyl and imidazolium units were synthesized and applied as the electrolytes for dye-sensitized solar cells (DSSCs). The fabricated all-solid-state DSSCs achieved a cell efficiency of ∼5.11% at 55 °C under the simulated air mass 1.5 solar spectrum illuminations at 100 mW cm⁻² because of the enhanced light harvesting capability of the electrolyte. To further improve the cell efficiency, 1-propyl-3-methylimidazolium iodine (PMII), was added into the electrolytes as a crystal growth inhibitor. These fabricated devices showed an enhanced power conversion efficiency (PCE) of ∼6.55% at 45 °C under the simulated air mass 1.5 solar spectrum illuminations at 50 mW cm⁻², and a superior long-term stability. The cyanobiphenyl-functionalized ionic crystal based electrolytes have expanded our vision to explore new types of all-solid-state electrolytes for high-efficiency DSSCs.