A Pt-free pristine monolithic carbon aerogel counter electrode for dye-sensitized solar cells: up to 20% under dim light illumination.

In this work, pristine carbon aerogels (CAs) were used as Pt-free counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) by varying the molar ratio of their precursors. Pristine mesoporous CAs with controlled resorcinol (R)/formaldehyde (F) and resorcinol (R)/sodium carbonate (C) molar ratios were successfully prepared. The as-prepared CAs were synthesized via a polymeric sol-gel reaction and were labeled as CA-O, CA-Q, CA-F, CA-C, and CA-G. The DSSCs using the as-prepared CA-C CE gave the best power conversion efficiency (PCE, η), 9.08 ± 0.01%, among all the CA CEs. The CA-C CE is further applied to an indoor T5 light source system with an impressive η value of 20.1 ± 0.60% at 2.18 mW cm-2 (T5 lamp with 7000 lux). Moreover, the hardness of CA-C CE is 3.01 GPa (Brinell hardness test), which is comparable to that of the FTO/glass substrate. As a result, the CA-C CE shows great potential to replace traditional CEs based on the Pt/FTO/glass in DSSCs.