Exceedingly Cheap Perovskite Solar Cells Using Iron Pyrite Hole Transport Materials

Methyl ammonium lead tri iodide perovskite solar cells attracted significant interest due to their high efficiency over 20% using polytriarylamine polymer (PTAA) and spiro-OMeTAD (Spiro). While the perovskite absorber material is relatively inexpensive to fabricate, the hole transport material is considerably expensive. Here we address the problem of cost by applying the vastly abundant mineral iron pyrite (FeS2) as a hole transporting material in perovskite solar cells. We report a power conversion efficiency of 11.2% using n-i-p configuration where the perovskite is an intrinsic semiconductor, TiO2 as an electron acceptor (n-type layer), and FeS2 as hole transporter (p-type layer). We show through photoluminescence quenching studies that pyrite transfers holes at least as efficiently as Spiro. Cost analysis of the pyrite HTM and Spiro indicates that currently, pyrite is > 300 times cheaper to produce for 1 m(2) modules.