Carbon nanotubes as an efficient hole collector for high voltage methylammonium lead bromide perovskite solar cells

A high open circuit voltage ( V OC ) close to 1.4 V under AM 1.5, 100 mW cm −2 conditions is achieved when carbon nanotubes (CNTs) are used as a hole conductor in methyl ammonium lead bromide (MAPbBr 3 ) perovskite solar cells. Time-resolved photoluminescence and impedance spectroscopy investigations suggest that the observed high V OC is a result of the better charge extraction and lower recombination of the CNT hole conductor. Tandem solar cells with all perovskite absorbers are demonstrated with a MAPbBr 3 /CNT top cell and a MAPbI 3 bottom cell, achieving a V OC of 2.24 V in series connection. The semitransparent and high voltage MAPbBr 3 /CNT solar cells show great potential for applications in solar cell windows, tandem solar cells and solar driven water splitting. A high open circuit voltage close to 1.4 V is achieved when carbon nanotubes are used as a hole conductor in methyl ammonium lead bromide perovskite solar cells.