Perovskite and chalcogenide quantum dots (QDs) are important nano semiconductors. It has been a challenge to synthesize heterostructural QDs combining perovskite and chalcogenide with tailorable photoelectronic properties. In this report, heterostructural CsPbX3-PbS (X = Cl, Br, I) QDs were successfully synthesized via a room temperature in situ transformation route. The CsPbX3-PbS QDs show a tunable dual emission feature with the visible and near-infrared (NIR) photoluminescence (PL) corresponding to CsPbX3 and PbS, respectively. Typically, the formation and evolution of the heterostructural CsPbBr3–PbS QDs with reaction time was investigated. Femtosecond transient absorption spectroscopy (TAS) was applied to illuminate the exciton dynamics in CsPbBr3–PbS QDs. The mild synthetic method and TAS proved perovskite to PbS energy transfer may pave the way toward highly efficient QD photovoltaic and optoelectronic devices.

Single-crystal perovskites with excellent photophysical properties are considered to be ideal materials for optoelectronic devices, such as lasers, light-emitting diodes and photodetectors. However, the growth of large-scale perovskite single-crystal films (SCFs) with high optical gain by vapor-phase epitaxy remains challenging. Herein, we demonstrated a facile method to fabricate large-scale thin CsPbBr3 SCFs (∼300 nm) on the c-plane sapphire substrate. High temperature is found to be the key parameter to control low reactant concentration and sufficient surface diffusion length for the growth of continuous CsPbBr3 SCFs. Through the comprehensive study of the carrier dynamics, we clarify that the trapped-related exciton recombination has the main effect under low carrier density, while the recombination of excitons and free carriers coexist until free carriers plays the dominate role with increasing carrier density. Furthermore, an extremely low-threshold (∼8 μJ cm–2) amplified spontaneous emission was achieved at room temperature due to the high optical gain up to 1255 cm–1 at a pump power of 20 times threshold (∼20 P th). A microdisk array was prepared using a focused ion beam etching method, and a single-mode laser was achieved on a 3 μm diameter disk with the threshold of 1.6 μJ cm–2. Our experimental results not only present a versatile method to fabricate large-scale SCFs of CsPbBr3 but also supply an arena to boost the optoelectronic applications of CsPbBr3 with high performance.

Miniaturized laser is the key element for integrated on-chip photonic device. Semiconductor materials are excellent candidates for gain medium of microscale laser, especially for nanowire (NW) based lasers. However, optical diffraction law constrains the footprint of photonic NW based device with the scale of half wavelength. [1] While in hybrid metal-semiconductor plasmonic nanostructures, photon energy could be coupled into collective electron oscillations in the form of surface plasmon polaritons (SPPs) at a metal-dielectric interface, [2][3][4] which therefore provide an effective solution to overcome optical diffraction limit. Similar to photonic laser, plasmonic lasers get amplification of SPPs by energy transfer from nonradiative part excitons of semiconductor material, where semiconductor severs as the gain media driving the inversion of SPP population at the metal-dielectric interface. [5][6][7] The SPP lasers show superior capabilities in strong light-matter interaction, which have potential applications in integrated photonics, biosensors, and quantum information technologies. [8][9][10] A series of inorganic II-VI and III-V compound semiconductor plasmonic NW lasers have been achieved in GaN, ZnO, and CdS NWs [11][12][13][14][15] at room temperature, because these NWs gain medium produce sufficient gain to overcome the high losses in metals. The fabrication procedures usually require extreme conditions such as high-temperature or low-pressure conditions, leading to high cost. However, till now the thresholds of the resulting lasers are still high, low-cost gain materials with excellent gain characteristics are in urgent need to be exploited to overcome these problems.Recently, organic-inorganic lead halide perovskites (CH 3 NH 3 PbX 3 , X = Cl, Br, I) have attracted intensive attentions for their huge potential in photovoltaics, with a power conversion efficiency exceeded 22.1% in solar cells. [16] On the other hand, lead halide perovskites have emerged as promising optical gain materials for achieving low-threshold plasmonic lasers owing to their excellent optical properties in a wide spectrum range, such as large absorption coefficients, high photoluminescence (PL) quantum yield, and low nonradiative recombination rates. [17][18][19][20][21] In past few years, SPP lasers have been investigated in hybrid perovskites. For instance, Kao et al. demonstrated enhanced localized surface plasmonic lasing performance in solution-processed CH 3 NH 3 PbI 3 perovskite films in Plasmonic nanolaser holds great potential in breaking down the diffraction limit of conventional optics to the deep sub-wavelength regime and in ultrafast lasing dynamics. However, plasmonic laser devices are constrained in practical applications due to their high cost and high thresholds. All-inorganic cesium lead halide perovskites are promising solutions for their excellent optical gain properties and high emission efficiency. In this work, high-quality single-crystalline CsPbBr 3 perovskite nanowires (NWs) are synthesized by chemical ...