Confining Metal-Halide Perovskites in Nanoporous Thin Films

TL;DR

This study demonstrates that confining metal-halide perovskites within nanoporous thin films enables control over their optical properties, enhances stability, and facilitates the fabrication of efficient, color-tuned optoelectronic devices.

Contribution

It introduces a novel method of growing perovskite nanocrystals within nanoporous templates, achieving size control, improved stability, and device integration without colloidal stabilization.

Findings

Pore size reduction causes significant blue shift in emission.

Confinement enhances photoluminescence stability.

Demonstrated electroluminescent diodes with narrow, blue-shifted emission.

Abstract

Controlling size and shape of semiconducting nanocrystals advances nanoelectronics and photonics. Quantum confined, inexpensive, solution derived metal halide perovskites offer narrow band, color-pure emitters as integral parts of next-generation displays and optoelectronic devices. We use nanoporous silicon and alumina thin films as templates for the growth of perovskite nanocrystallites directly within device-relevant architectures without the use of colloidal stabilization. We find significantly blue shifted photoluminescence emission by reducing the pore size; normally infrared-emitting materials become visibly red, green-emitting materials cyan and blue. Confining perovskite nanocrystals within porous oxide thin films drastically increases photoluminescence stability as the templates auspiciously serve as encapsulation. We quantify the template-induced size of the perovskite crystals in nanoporous silicon with microfocus high-energy X-ray depth profiling in transmission geometry, verifying the growth of perovskite nanocrystals throughout the entire thickness of the nanoporous films. Low-voltage electroluminescent diodes with narrow, blue-shifted emission fabricated from nanocrystalline perovskites grown in embedded nanoporous alumina thin films substantiate our general concept for next generation photonic devices.