HIGH-EFFICIENT SOLID-STATE PEROVSKITE SOLAR CELL WITHOUT LITHIUM SALT IN THE HOLE TRANSPORT MATERIAL

Abstract

CH 3 NH 3 PbX ( X = Br , I , Cl ) perovskites have recently been used as light absorbers in hybrid organic–inorganic solid-state solar cells, with efficiencies above 15%. To date, it is essential to add Lithium bis(Trifluoromethanesulfonyl)Imide ( LiTFSI ) to the hole transport materials (HTM) to get a higher conductivity. However, the detrimental effect of high LiTFSI concentration on the charge transport, DOS in the conduction band of the TiO 2 substrate and device stability results in an overall compromise for a satisfactory device. Using a higher mobility hole conductor to avoid lithium salt is an interesting alternative. Herein, we successfully made an efficient perovskite solar cell by applying a hole conductor PTAA (Poly[bis(4-phenyl) (2,4,6-trimethylphenyl)-amine]) in the absence of LiTFSI . Under AM 1.5 illumination of 100 mW/cm2, an efficiency of 10.9% was achieved, which is comparable to the efficiency of 12.3% with the addition of 1.3 mM LiTFSI . An unsealed device without Li + shows interestingly a promising stability.