Towards Lead-Free Perovskite Solar Cells: Hurdles and Prospects

Consistent increase in the power conversion efficiency (PCE) of lead-based halide perovskite solar cells (PSCs) has been observed over the past one decade. PCE is currently slightly above 25 %. Various components within PSC devices are responsible for cell performance, however the most important component is the perovskite layer. Lead (Pb) has taken the lead in the achievement of impressive PCEs of PSCs; Pb has been a major part of the perovskite structure because of its excellent optoelectronic properties. Pb is however known to be toxic, with irreversible detrimental consequences upon human exposure. Plying less expensive routes such as solution process techniques in obtaining direct current electricity through photovoltaics is considered a huge advancement in photovoltaic technology; nevertheless, technological advancement should not be detrimental to health. Here, we provide up-to-date highlights on major progresses made towards achieving high efficiency in the fabrication of lead-free perovskites for photovoltaics application and hence make considerable suggestions on ways forward.