Mesoporous Si Nanowire Templated Controlled Fabrication of Organometal Halide Perovskite Nanoparticles with High Photoluminescence Quantum Yield for Light-Emitting Applications

We report on the controlled fabrication of CH3NH3PbI3 perovskite nanoparticles (NPs) on a mesoporous Silicon nanowire (NW) template for the first time and study the mechanism of its high photoluminescence (PL) quantum yield. Crystalline perovskite NPs are grown by spin-coating of perovskite precursor on the surface of mesoporous Si NWs fabricated by a metal-assisted chemical etching method. We have tuned the size of the perovskite NPs (5-70 nm) and its photophysical properties by controlling the porosity of the Si NWs and perovskite precursor concentrations. The as-grown perovskite NPs on Si NWs show enhancement in PL intensity by more than 1 order of magnitude as compared to that of the perovskite film on a Si substrate. Depending on the size of the perovskite NPs, the center of the PL peak of the of NPs shows a large blue-shift as compared to that of the perovskite film. A detailed systematic study reveals that decrease in particle size and the quantum confinement in perovskite NPs are primarily responsible for the enhanced yield as well as blue-shift of PL. With the help of plasma-treated Si NW template, the contribution of the photon recycling effect to the enhanced PL of NPs was quantitatively assessed and found to be only 10%. The PL quantum yield of the perovskite NPs was measured to be 9.82% as compared to the low yield (0.69%) of the perovskite film. Time-resolved PL analysis of perovskite NPs show a longer lifetime of carriers due to negligible nonraditative recombination in the NPs, which is consistent with the high PL yield. This study demonstrates an easy and cost-effective fabrication of perovskite NPs on a novel mesoporous Si NWs template, which is a versatile platform, and it unravels the mechanism behind its superior photophysical properties, which is significant for different light-emitting and display applications.