Design of a specific two–dimensional layered V2C counter electrode for highly effective and stable rigid and flexible quasi–solid–state dye–sensitized solar cells

Abstract

Exploring Pt–free counter electrode catalysts for quasi–solid–state DSCs (QSDSCs) is significant for overcoming the high cost of Pt counter electrodes and their insufficient contact with the electrolyte. Herein, a two–dimensional (2D) layered MXene, V2C, is synthesized via a simple etching method as a counter electrode in QSDSCs. The impact of the etching time on the catalytic activity toward the regeneration of the I–/I3– redox couple in a quasi–solid–state electrolyte is investigated. After optimization, the V2C etched for 48 h shows a high catalytic activity caused by the constructed unique 2D lamellar structure, which can provide smooth diffusion channels for the penetration of the quasi–solid–state electrolyte to form sufficient contact between the V2C counter electrode and the electrolyte. As a result, the QSDSCs using the 2D layered V2C counter electrode generate a power conversion efficiency (PCE) of 7.48%. Moreover, the catalytic behavior of V2C is further improved by K+ intercalation, and the PCE value of the corresponding QSDSCs is enhanced to 8.30% under standard illumination (1.0 Sun) and to 10.19% under weak illumination (0.1 Sun). Meanwhile, the K+–intercalated V2C shows excellent stability, and 87.9% of the initial PCE of the device is retained after 1050 h in a durability test. This research is expected to provide meaningful support for the exploration of new counter electrode materials and the improvement of the contact between the counter electrode and quasi–solid–state electrolyte for the pursuit of high–performance and low–cost QSDSCs.