Journal
ACS NANO
Volume 9, Issue 1, Pages 687-695Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nn5061207
Keywords
whispering gallery mode (WGM); lasing; layered materials; lead iodide; hexagonal platelet; Fabry-Perot cavity
Categories
Funding
- Singapore National Research Foundation through a NRF fellowship grant [NRF-RF2009-06]
- Singapore National Research Foundation through a Competitive Research Program grant [NRF-CRP-6-2010-2]
- Ministry of Education [MOE2011-T2-2-051, MOE2013-T2-1-049]
- Nanyang Technological University (NTU) [M58113004]
- NTU [M4080514]
- SPMS collaborative Research Award [M4080536]
- Ministry of Education (MOE) [MOE2013-T2-1-081]
- Singapore National Research Foundation [NRF-CRP5-2009-04]
- Singapore-Berkeley Research Initiative for Sustainable Energy (SinBerRISE) CREATE Programme
- Generalitat de Catalunya [2014 SGR 1638]
- ICREA Funding Source: Custom
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We report on the synthesis and optical gain properties of regularly shaped lead iodide (PbI2) platelets with thickness ranging from 10-500 nm synthesized by chemical vapor deposition methods. The as-prepared single crystalline platelets exhibit a near band edge emission of similar to 500 nm. Whispering gallery mode (WGM) lasing from individual hexagonal shaped PbI2 platelets is demonstrated in the temperature-range of 77-210 K, where the lasing modes are supported by platelets as thin as 45 nm. The finite-difference time-domain simulation and the edge-length dependent threshold confirm the planar WGM lasing mechanism in such hexagonal shaped PbI2 platelet. Through a comprehensive study of power-dependent photoluminescence (PL) and time-resolved PL spectroscopy, we ascribe the WGM lasing to be biexcitonic in nature. Moreover, for different thicknesses of platelet, the lowest lasing threshold occurs in platelets of similar to 120 nm, which attributes to the formation of a good FabryPerot resonance cavity in the vertical direction between the top and bottom platelet surfaces that enhances the reflection. Our present study demonstrates the feasibility of planar light sources based on layered semiconductor materials and that their thickness-dependent threshold characteristic is beneficial for the optimization of layered material based optoelectronic devices.
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