Enhanced quantum yield of photoluminescent porous silicon prepared by supercritical drying
Abstract
The effect of supercritical drying (SCD) on the preparation of porous silicon (pSi) powders has been investigated in terms of photoluminescence (PL) efficiency. Since the pSi contains closely spaced and possibly interconnected Si nanocrystals (<5 nm), pore collapse and morphological changes within the nanocrystalline structure after common drying processes can affect PL efficiency. We report the highly beneficial effects of using SCD for preparation of photoluminescent pSi powders. Significantly higher surface areas and pore volumes have been realized by utilizing SCD (with CO2 solvent) instead of air-drying. Correspondingly, the pSi powders better retain the porous structure and the nano-sized silicon grains, thus minimizing the formation of non-radiative defects during liquid evaporation (air drying). The SCD process also minimizes capillary-stress induced contact of neighboring nanocrystals, resulting in lower exciton migration levels within the network. A significant enhancement of the PL quantum yield (>32% at room temperature) has been achieved, prompting the need for further detailed studies to establish the dominant causes of such an improvement.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 11, 2016
- Source ID
- 10.1063/1.4947084
Entities
People
- Armando Loni
- Dokyoung Kim
- Gael Gautier
- Jinmyoung Joo
- Leigh T. Canham
- Michael J. Sailor
- Thomas Defforge
- Z. Y. Li
Organizations
- Defense Advanced Research Projects Agency
- University of Birmingham
- University of California
- University of Ulsan