Facile growth of perovskite nanoparticles confined on dimension-controlled Si nanorod arrays for various promising photophysical applications

In this study, a facile growth of hybrid perovskite nanoparticles (NPs) has been demonstrated on mesoporous, high-aspect ratio, morphology-controlled Si nanorod (NR) arrays. A generic method of directly confining perovskite nanocrystallites (average size <7 nm) on a mesoporous substrate without the use of colloidal stabilization was introduced. The perovskite NPs coated on dimension-and position-controlled Si NR arrays were systematically investigated by their various photophysical properties such as optical reflectance, cathodoluminescence (CL), and photoluminescence (PL) behaviors at both room temperature and low temperature. The dimension and position of the Si NR arrays were controlled by e-beam lithography followed by selective metal-assisted chemical etching (MACE). Organic-inorganic perovskite NPs were synthesized on the surface of Si NR array by spin coating of perovskite precursor solution and followed by annealing. The porous and rough sites on the surface of the NR arrays acted as nucleation centers for the formation of perovskite NPs. Due to the excitonic recombination of CH3NH3PbBr3, the NPs confined on the various NR templates exhibited strong PL emission in the 505-510 nm region. Furthermore, due to greater radiative recombination and lesser carrier trapping in the NPs, the PL and CL emission intensities of the perovskite NPs localized on the surface of the NR array were dramatically increased (PL enhancement factor similar to 7.7, when NR aspect ratio similar to 17.2) as compared to the bulk perovskite microcrystals. The low-temperature PL study revealed higher exciton binding energy of the NPs as compared to the bulk microcrystalline film. A systematic investigation revealed that the optical absorption, as well as the emission color of the perovskite NPs, can be tuned by the aspect ratio of the Si NR arrays. The results of our studies indicate the application of bandgap engineering of perovskite nanocrystals through confinement in a mesoporous, well-organized, regularly-ordered template as a powerful tool for tuning the emission wavelength in next-generation photonic sources. Furthermore, the important findings on the periodic array of photoactive nanoscale materials introduced in this manuscript may open up huge opportunities in numerous cutting-edge applications such as light emitting diode arrays, photodetector arrays, individually addressable devices, display devices with controlled pixel size and pixel density, etc.

Automated summary

A facile growth of hybrid perovskite nanoparticles (NPs) has been demonstrated on mesoporous, high-aspect ratio, morphology-controlled Si nanorod (NR) arrays. The perovskite NPs coated on dimension- and position-controlled Si NR arrays exhibited strong photoluminescence (PL) and cathodoluminescence (CL) emission properties, with enhanced intensity compared to bulk perovskite microcrystals. The findings suggest the potential applications of perovskite nanocrystals in next-generation photonic sources. Evaluation: 8/10