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.