A (CH 3 NH 3 ) 3 Bi 2 I 9 Perovskite Based on a Two-Step Deposition Method: Lead-Free, Highly Stable, and with Enhanced Photovoltaic Performance

Abstract

Despite achieving a higher efficiency, lead-based perovskite solar cells (PSCs) suffer from leakage of highly toxic Pb into the atmosphere. On the contrary, methyl ammonium bismuth halide (MBI) has gained enormous attention as a light absorber because of its low toxicity and air stability. Herein, we developed high-performance, lead-free PSCs by employing a modified two-step deposition method with FTO/CL-TiO 2 /m-TiO 2 /MBI/Spiro-MEOTAD/Au device architecture [where FTO: fluorine doped tin oxide; MBI: (MA) 3 Bi 2 I 9 ; MEOTAD: 2,2′,7,7′-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene]. The PSCs fabricated by the two-step deposition method showed a good power-conversion efficiency of 0.41 %, along with a high open circuit voltage of 870 mV, and were found to be highly stable up to 60 days under atmospheric conditions (humidity ∼40–50 %). The film quality of the MBI was found to be superior by introducing modified two-step deposition method over one-step deposition. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim