Performance of low-cost mixed cationic carbon-based solar cells prepared through compositional engineering under ambient conditions

Abstract

Perovskite solar cells (PSC) have reached a record efficiency of up to 25.2 % in a matter of few years. This has spawned a lot of interest in investigating the commercial scalability of the perovskites by reducing the cost. Carbon can act as a cheaper alternative to gold and aluminium to act as counter electrode. In the present study, we have tuned the perovskite layer by the addition of FA (Formamidinium) and Cs (Cesium) through compositional engineering. The optimized configuration of perovskite was then utilized in carbon monolithic electrode stack to form a carbon-based perovskite solar cell. Emphasis is more on the performance of these carbon-based PSC. Three batches of carbon-based PSC were prepared with two-hole transport layers (P3HT, Spiro-OMeTAD) and one with no hole transport layer. All the carbon-based PSC were then subjected to EIS studies. The carbon-based HTL-Free PSC had a power conversion efficiency (PCE) of up to 9.5 % while cells with HTLs as P3HT and Spiro-OMeTAD had 8.5 % and 13.4 %, respectively. Stability wise, HTL-free devices performed exceedingly well (up to 76 days). Under endurance testing against light and heat, P3HT- based devices managed to retain 75 % of PCE after 25 h constant illumination and performed better than HTL-free and Spiro-OMeTAD based cell under thermal stress of up to 240 ℃.