A comparative meta-analysis of gains in efficiency in Pb- and Sn-based perovskite solar cells over the last decade

Abstract

Perovskite solar cells have seen rapid development over the last decade due to their potential to surpass current market-leading solar cell technologies. Power conversion efficiency values of perovskite solar cells have reached more than 25 %, making them comparable to their market-leading silicon-based counterparts with comparatively few years of development. Whilst large-scale trials are ongoing, the long-term stability of perovskite materials remains a significant challenge in their deployment. The first successful perovskite-based solar cells were lead-based (Pb-based). Environmental concerns surrounding Pb-based perovskites are a significant impediment to their application in industry leading to a substantial increase in research into alternatives that are more environmentally sound. The meta-analysis study presented in this paper intends to harvest efficiency and synthetic method data from the literature to chart the progress of efficiency over the last decade of BOTH Pb- and Sn-based perovskite solar cells. We then use these data to test the hypothesis: “Did the advancements in the development of earlier Pb-based perovskite solar cells mean the efficiency of Sn-based alternatives developed at a faster rate?”. The meta-analysis found that materials engineering, i. e., identifying the suitable materials for perovskite, electron and transport layers and the solution and fabrication process contributed significantly to the rapid annual efficiency growth rates in Pb-based perovskite solar cells (more than 25 %) from 2011 to 2014. More steady annual efficiency growth rates (2 to 7 %) from 2014 to 2021 are attributed to more advanced compositional engineering, such as optimizing bandgap and addressing stability problems, solution and additive engineering with regard thermal annealing, ageing, doping, improving crystallinity and passivating defects. Ultimately, this report states the challenges Sn-based perovskite materials face and improvements that will have to be made to become successful on a commercial scale. One of our key findings is the increase in efficiency from 5 % in 2014 to 13 % in 2020 of Sn-based perovskites making them one of the main contenders to replace Pb-based perovskites. However, significant challenges remain, including reducing their instability and increasing their efficiencies beyond 20 % to make them competitive against their Pb-based counterparts.