High‐Efficiency Perovskite Solar Cells Based on the Black Polymorph of HC(NH2)2PbI3

Perovskite solar cells with power conversion efficiencies exceeding 16% at AM 1.5G one sun illumination are developed using the black polymorph of formamidnium lead iodide, HC(NH2)2PbI3. Compared with CH3NH3PbI3, HC(NH2)2PbI3 extends its absoprtion to 840 nm and shows no phase transition between 296 and 423 K. Moreover, a solar cell based on HC(NH2)2PbI3 exhibits photostability and little I–V hysteresis.