Dongqin Bi 1 , Wolfgang Tress 2 , * , M. Ibrahim Dar 2 , 3 , Peng Gao 3 , Jingshan Luo 2 , Clémentine Renevier 2 , Kurt Schenk 4 , Antonio Abate 2 , Fabrizio Giordano 2 , Juan-Pablo Correa Baena 1 , Jean-David Decoppet 2 , Shaik Mohammed Zakeeruddin 2 , Mohammad Khaja Nazeeruddin 3 , Michael Grätzel 2 , Anders Hagfeldt 1
01 January 2016
Researchers developed a perovskite solar cell with high power-conversion efficiency (>20%) and intense electroluminescence yield (0.5%).
We report on a new metal halide perovskite photovoltaic cell that exhibits both very high solar-to-electric power-conversion efficiency and intense electroluminescence. We produce the perovskite films in a single step from a solution containing a mixture of FAI, PbI 2, MABr, and PbBr 2 (where FA stands for formamidinium cations and MA stands for methylammonium cations). Using mesoporous TiO 2 and Spiro-OMeTAD as electron- and hole-specific contacts, respectively, we fabricate perovskite solar cells that achieve a maximum power-conversion efficiency of 20.8% for a PbI 2/FAI molar ratio of 1.05 in the precursor solution. Rietveld analysis of x-ray diffraction data reveals that the excess PbI 2 content incorporated into such a film is about 3 weight percent. Time-resolved photoluminescence decay measurements show that the small excess of PbI 2 suppresses nonradiative charge carrier recombination. This in turn augments the external electroluminescence quantum efficiency to values of about 0.5%, a record for perovskite photovoltaics approaching that of the best silicon solar cells. Correspondingly, the open-circuit photovoltage reaches 1.18 V under AM 1.5 sunlight.