Addictive-assisted construction of all-inorganic CsSnIBr2 mesoscopic perovskite solar cells with superior thermal stability up to 473 K

The poor stability of hybrid organic-inorganic perovskite is one of crucial problems limiting the practical application of the perovskite solar cells (PSCs). All-inorganic lead-free perovskite materials, with Cs replacing the organic cations and Sn replacing Pb, have shown great potential in achieving high thermal stability. However, tin-based perovskites have inevitably suffered from severe bulk recombination, attributed to Sn vacancies. In this work, we obtain CsSnIBr2 thin films with low Sn vacancy assisted by the addition of hypophosphorous acid (HPA). The HPA additive here as complexant is demonstrated to be capable of speeding up the nucleation process while inhibiting the formation of Sn4+ during the formation process of CsSnIBr2 thin films. With a mesoscopic architecture, the CsSnIBr2 PSCs exhibit efficiency-loss free in 77 days and remarkably stable power output within 9 hours at high temperatures up to 473 K.