Publication date: 1st July 2014
Organometal halide perovskites are considered a paradigm shift in the field of third generation solar cells. Various strategies are underway to further engineer the perovskite constituents to improve their properties and thereby enhance the corresponding solar cell efficiency. Here we report an interesting strategy to partially incorporate F- ion within the perovskite structure in the form of BF4- molecular ion. Importantly, I- and BF4- both have nearly same ionic radius which makes the incorporation of BF4- feasible in the structure. The incorporation of BF4- within the perovskite structure is supported by the elemental mapping and ATR-FTIR studies. The synthesized hybrid perovskite CH3NH3PbI(3-x)(BF4)x shows sharp absorption onset at 760 nm and near band edge luminescence at 766 nm. The BF4- molecular ion substituted hybrid perovskite also shows one order of magnitude enhancement in the low frequency electrical conductivity as compared to the conventional perovskite (CH3NH3PbI3). When tested in a photo-sensor device architecture the modified perovskite shows over four orders of magnitude photosensitivity under AM1.5 radiation.