mixture at 150 °C for 2 min and then Cs-oleate solution (0.4 mL in ODE) was quickly injected. After 5 s, the reaction mixture was cooled by the ice-water bath to room temperature.

On-chip photonic information processing systems require great research efforts toward miniaturization of the optical components. However, when approaching the classical diffraction limit, conventional dielectric lasers with all dimensions in nanoscale are difficult to realize due to the ultimate miniaturization limit of the cavity length and the extremely high requirement of optical gain to overcome the cavity loss. Herein, we have succeeded in reducing the laser size to subwavelength scale in three dimensions using an individual CsPbBr perovskite nanocuboid. Even though the side length of the nanocuboid laser is only ∼400 nm, single-mode Fabry-Pérot lasing at room temperature with laser thresholds of 40.2 and 374 μJ/cm for one- and two-photon excitation has been achieved, respectively, with the corresponding quality factors of 2075 and 1859. In addition, temperature-insensitive properties from 180 to 380 K have been demonstrated. The physical volume of a CsPbBr nanocuboid laser is only ∼0.49λ (where λ is the lasing wavelength in air). Its three-dimensional subwavelength size, excellent stable lasing performance at room temperature, frequency up-conversion ability, and temperature-insensitive properties may lead to a miniaturized platform for nanolasers and integrated on-chip photonic devices in nanoscale.

Destabilizing the polar order unexpectedly boosts the ferroelectric photovoltaic performance in bismuth ferrite.

The efficiency of antimony selenide (Sb2Se3) solar cells has been improved from <2% to >10% within only 7 years, but fundamental properties at the heterojunction interface such as the charge carrier transfer and the trap state localizing process has not been studied yet. Here, the carrier competing dynamics in Sb2Se3-based heterojunction has been systematically investigated. We find the competition between the band-edge electron transfer and the trapping process in CdS/Sb2Se3 will result in less-efficient charge separation and hence low open circuit voltage in photovoltaic devices. In contrast, the hot electron extraction at the SnO2/Sb2Se3 interface is nearly an order of magnitude faster than the trapping process, which can effectively escape the trapping carrier loss and potentially lead to higher open-circuit voltages. Our results reveal the hidden role of the buffer interface in the ultrafast charge extraction and provide a potential strategy to improve the performance of Sb2Se3-based solar cells.