Low-threshold amplified spontaneous emission and lasing from colloidal nanocrystals of caesium lead halide perovskites.

Sergii Yakunin,Georgian Nedelcu,Manfred Fiebig,Markus Humer,Maksym V Kovalenko,Gabriele De Luca,Maryna I Bodnarchuk,Wolfgang Heiss,Franziska Krieg,Loredana Protesescu

doi:10.1038/ncomms9056

Abstract

Metal halide semiconductors with perovskite crystal structures have recently emerged as highly promising optoelectronic materials. Despite the recent surge of reports on microcrystalline, thin-film and bulk single-crystalline metal halides, very little is known about the photophysics of metal halides in the form of uniform, size-tunable nanocrystals. Here we report low-threshold amplified spontaneous emission and lasing from ∼10 nm monodisperse colloidal nanocrystals of caesium lead halide perovskites CsPbX3 (X=Cl, Br or I, or mixed Cl/Br and Br/I systems). We find that room-temperature optical amplification can be obtained in the entire visible spectral range (440–700 nm) with low pump thresholds down to 5±1 μJ cm−2 and high values of modal net gain of at least 450±30 cm−1. Two kinds of lasing modes are successfully observed: whispering-gallery-mode lasing using silica microspheres as high-finesse resonators, conformally coated with CsPbX3 nanocrystals and random lasing in films of CsPbX3 nanocrystals.

Highlights

Metal halide semiconductors with perovskite crystal structures have recently emerged as highly promising optoelectronic materials
We have recently shown that high optoelectronic quality is accessible in fully inorganic CsPbX3 analogues, when these compounds are synthesized in the form of colloidal nanocrystals (NCs)[22]
For thin films of CsPbX3 NCs, we report the observation of amplified spontaneous emission (ASE), tunable over most of the visible range (440–700 nm) with low pump thresholds down to 5±1 mJ cm À 2 and high values of modal net gain of at least 450 cm À 1

Summary

Introduction

Metal halide semiconductors with perovskite crystal structures have recently emerged as highly promising optoelectronic materials. Common metal chalcogenide colloidal quantum dots such as CdSe NCs need to be extremely small (r5 nm) to emit in the blue–green, and as-synthesized they exhibit rather low PL QYs of r5% due to mid-gap trap states. They are chemically and photochemically unstable, and require coating with an epitaxial layer of a more chemically robust, wider-gap semiconductor, such as CdS. We realize two different lasing regimes for CsPbX3 NCs depending on the resonator configuration: whispering-gallery-mode (WGM) lasing using single silica microsphere resonators, conformally coated with CsPbX3 NCs, and random lasing in CsPbX3 NC films

Methods

Results

Conclusion