Abstract
Although optical refrigeration---``laser cooling''---is an interesting physical phenomenon, its practical implementation in solid-state devices is still difficult due to material limitations. Here, the authors investigate the up-converted photoluminescence (anti-Stokes photoluminescence) from optically thin films and thick crystals of CH${}_{3}$NH${}_{3}$PbI${}_{3}$ perovskite. They discuss the competition between the anti-Stokes photoluminescence and the photon reabsorption, and demonstrate that as a result of the high luminescence efficiency, up-conversion gain can occur even in optically thick CH${}_{3}$NH${}_{3}$PbI${}_{3}$ single crystals. The optimal excitation energy for the maximum up-conversion gain in perovskites was determined experimentally. These important physical insights lay the foundations for the perovskite-based devices for optical refrigeration.
Highlights
In recent years, the lead halide perovskite semiconductors have been receiving significant attention as a novel material for optical devices
We introduce an up-conversion gain spectrum defined by the intensity difference between the AS-PL excitation (PLE) and Stokes PLE (S-PLE) spectra
With the following detailed analysis of the PLE maps, we discuss the effect of photon reabsorption as well as the anti-Stokes PL (AS-PL)
Summary
The lead halide perovskite semiconductors have been receiving significant attention as a novel material for optical devices. This is surprising, because these two materials, GaAs and lead halide perovskites, have very similar PL and absorption properties [8,30] It is an open question why laser cooling is difficult to achieve in the III–V semiconductors [26,27,28] but perovskites can be cooled down very effectively [29]. Most of the up-converted PL cannot be extracted from optically thick samples due to a strong reabsorption which leads to sample heating For this reason, the previous investigations on laser cooling in bulk semiconductors were performed on thin samples [26,27,28,29]. The broad shape of the up-conversion gain spectrum implies that large anharmonic and overdamped phonon play an important role for the efficient up-conversion process in the perovskites
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
