High Charge Carrier Mobilities and Lifetimes in Organolead Trihalide Perovskites

摘要

A new generation of thin-film photovoltaic cells based on organo-metal halide perovskite absorbers has recently emerged with extraordinary power conversion efficiencies (PCE). Initial PCEs reported around 10 % were soon superseded by values ranging from 12% to over 15% as materials control and device protocol improved. Methylammonium lead trihalide perovskite materials allow low-cost solution processing and absorb broadly across the solar spectrum, making them an exciting new component for clean energy generation. Interestingly, two different device concepts have appeared: in one, the lead halide compound CH_3NH_3PbI_3 is deposited on the surface of mesoporous TiO_2, which is then infiltrated with the solid-state hole transporter spiro-OMeTAD. The resulting cell has an analogous structure to a conventional solid-state dye-sensitized solar cell, in which upon photoexcitation electrons transfer from an excited dye to the TiO_2 conduction band and subsequently diffuse to the contact. The first reported power conversion efficiencies of up to 9.7% for cells based on CH_3NH_3PbI_3 by far exceeded previous records achieved with cells employing dyes as absorbers (≤6%).