Effect of Carrier Thermalization Dynamics on Light Emission and Amplification in Organometal Halide Perovskites.
The remarkable rise of organometal halide perovskites as solar photovoltaic materials has been followed by promising developments in light-emitting devices, including lasers. Here we present unique insights into the processes leading to photon emission in these materials. We employ ultrafast broadband photoluminescence (PL) and transient absorption spectroscopies to directly link density dependent ultrafast charge dynamics to PL. We find that exceptionally strong PL at the band edge is preceded by thermalization of free charge carriers. Short-lived PL above the band gap is clear evidence of nonexcitonic emission from hot carriers, and ultrafast PL depolarization confirms that uncorrelated charge pairs are precursors to photon emission. Carrier thermalization has a profound effect on amplified stimulated emission at high fluence; the delayed onset of optical gain we resolve within the first 10 ps and the unusual oscillatory behavior are both consequences of the kinetic interplay between carrier thermalization and optical gain.
The MacDiarmid Institute for Advanced Materials and Nanotechnology and School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.
Kai
K
Chen
The MacDiarmid Institute for Advanced Materials and Nanotechnology and School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.
Alex J
AJ
Barker
The MacDiarmid Institute for Advanced Materials and Nanotechnology and School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.
Francis L C
FL
Morgan
The MacDiarmid Institute for Advanced Materials and Nanotechnology and School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.
Jonathan E
JE
Halpert
The MacDiarmid Institute for Advanced Materials and Nanotechnology and School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.
Justin M
JM
Hodgkiss
amplified stimulated emission; optical Kerr gate; photoluminescence; ultrafast spectroscopy