From femtosecond pulse-excited lasing, perovskite lasers have rapidly developed continuous-wave excited lasing, which is considered a crucial step toward electrically excited lasing. The next objective is to achieve electrically driven lasing, which follows continuous-wave lasing at room temperature.
Traditional epitaxially grown single crystal semiconductors with high charge carrier mobility m and high thermal conductivity typically exhibit small resistive heating in electric injection lasers that are currently on the market. Perovskites have small values despite having large and balanced charge carrier mobilities. The warm conductivity of MAPbI3 is 1-3 W m1 K1, which is a low rate compared to that of GaAs (50 W m1 K1).
As a result, nonradiative pathways that convert energy loss into heat cannot effectively dissipate it. As carriers occupy a wider energy range at a higher temperature, this failure will raise the lasing threshold, reducing the population inversion of any given transition and other issues like degradation and heat-induced defects.
A distributed-feedback (DFB) perovskite laser’s lowest electric excitation threshold would be as high as 24 mA/cm2. In addition, Joule heating would significantly reduce the external quantum efficiency under high current injection conditions in conventional perovskite light-emitting diode architectures used in laser devices. Consequently, heating the board is a bottleneck for creating perovskite-based electrically determined lasers.
A perovskite nanoplatelet laser on a diamond substrate that can effectively dissipate heat generated during optical pumping was demonstrated by a group of researchers, including Prof. Guohui Li, Prof. Shengwang Yu, Prof. Yanxia Cui of Taiyuan University of Technology, and Prof. Kaibo Zheng of Lund University.
The demonstrated laser has a lasing threshold of 52.19 J/cm2 and a Q factor of 1962. A thin SiO2 gap layer is also used to achieve tight optical confinement between the diamond substrate and the nanoplatelets. The structures’ electric field distributions indicate that a 200-nm-thick SiO2 gap reduces the diamond substrate’s leakage field and improves mode confinement in the MAPbI3 nanoplatelet at the same time.
Under optical pumping conditions, they looked at how temperature variations affected the heat dissipation in perovskite nanoplatelet lasers on the diamond substrate. Due to the inclusion of the diamond substrate, the laser exhibits a temperature sensitivity that is pump density-dependently low (less than 0.56 0.01 K cm2 J1).
The sensitivity is one to two orders of magnitude lower than that of perovskite nanowire lasers on glass substrates that have previously been reported. The high-warm conductivity precious stone substrate enables the nanoplatelet laser to work at a high siphon thickness. Electrically driven perovskite lasers could emerge from this study. Science China Materials published this work.
More information: Guohui Li et al, Efficient heat dissipation perovskite lasers using a high-thermal-conductivity diamond substrate, Science China Materials (2023). DOI: 10.1007/s40843-022-2355-6