Abstract
Announced as one of the top 10 research breakthroughs in 2016, perovskite solar cells (PSC) have advanced rapidly as an established photovoltaic technology. The power conversion efficiency (PCE) of PSCs has increased quickly from 3.8% to 23.7% within a period of just 7years. This very high PCE has been achieved by using perovskite compounds with lead (Pb) as the divalent metal ion. However, for further scale-up and commercialization, the toxicity of Pb has been identified as one of the key drawbacks for this technology. Numerous avenues for development of lead-free low-toxicity perovskite absorbers have been pursued. The unclear effect of using low-toxicity materials on optimal performance with suitable characteristicshas motivated the writing of this review. Results from low-toxicity perovskite solar cells utilizing partial or complete substitution of the Pb2+ cation as the absorber layer are discussed in detail. Moreover, we discuss the limitations of low-toxicity absorber materials. This review summarizes the key points of film quality control, degradation effect, Pb replacement suitability, and photovoltaic performance of reported low toxicity alternate perovskite absorbersfor PSCs.
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