近红外光探测能力强的光电探测器更有利于检测人体心率，而且探测范围覆盖红光与近红外光的宽带响应光电探测器能用于检测血氧饱和度，因此提升宽带响应光电探测器的红光与近红外光探测能力具有重要意义。然而，经典的二元体异质结宽带响应倍增型有机光电探测器通常由于活性层中给体/受体比例差异较大，导致器件对红光与近红外光的响应能力较弱甚至没有响应。本文通过用少量给体材料PCE10替代活性层P3HT∶IEICO?4F（100∶1）中部分P3HT的方法，制备了结构为ITO/PEDOT∶PSS/P3HT∶PCE10∶IEICO?4F（90∶10∶1）/Al的体异质结三元倍增型有机光电探测器。-20 V偏压下，三元器件获得紫外到近红外（330~810 nm）响应较均匀的EQE光谱，并且器件在660 nm和810 nm处的EQEs（134000%和147000%）是相同条件下二元器件的78倍和106倍，相应的探测灵敏度（5.4×10¹³ Jones和7.27×10¹³ Jones）分别提升了26倍和36倍。三元器件的红光和近红外光探测能力得到显著提升，为制备用于人体心率与血氧饱和度检测的高性能光电探测器提供了策略。

In recent years, all-inorganic halide perovskite quantum dots (QDs) have drawn attention as promising candidates for photodetectors, light-emitting diodes, and lasing applications. However, the sensitivity and instability of perovskite to moisture and heat seriously restrict their practical application to optoelectronic devices. Recently, a facile ligand-engineering strategy to suppress aggregation by replacing traditional long ligands oleylamine (OAm) during the hot injection process has been reported. Here, we further explore its thermal stability and the evolution of photoluminescence quantum yield (PLQY) under ambient environment. The modified CsPbBr3 QDs film can maintain 33% of initial PL intensity, but only 17% is retained in the case of unmodified QDs after 10 h continuous heating. Further, the obtained QDs with higher initial PLQY (91.8%) can maintain PLQY to 39.9% after being continuously exposed in air for 100 days, while the PLQY of original QDs is reduced to 5.5%. Furthermore, after adhering CsPbBr3 QDs on the surface of a micro SiO2 sphere, we successfully achieve the highly-efficient upconversion random laser. In comparison with the unmodified CsPbBr3 QDs, the laser from the modified CsPbBr3 QDs presents a decreased threshold of 79.81μJ/cm2 and higher quality factor (Q) of 1312. This work may not only provide a facile strategy to synthesize CsPbBr3 QDs with excellent photochemical properties but also a bright prospect for high-performance random lasers.

In the past decade, lead halide perovskites have emerged as potential optoelectronic materials in the fields of light-emitting diode, solar cell, photodetector, and laser, due to their low-cost synthesis method, tunable bandgap, high quantum yield, large absorption, gain coefficient, and low trap-state densities. In this review, we present a comprehensive discussion of lead halide perovskite applications, with an emphasis on recent advances in synthetic strategies, morphology control, and lasing performance. In particular, the synthetic strategies of solution and vapor progress and the morphology control of perovskite nanocrystals are reviewed. Furthermore, we systematically discuss the latest development of perovskite laser with various fundamental performances, which are highly dependent on the dimension and size of nanocrystals. Finally, considering current challenges and perspectives on the development of lead halide perovskite nanocrystals, we provide an outlook on achieving high-quality lead perovskite lasers and expanding their practical applications.

In recent years, halide perovskite nanostructures have had great advances and have opened up a bright future for micro/nanolasers. However, upconversion lasing by two-photon excitation with mode selection and high quality factor in one device is still rarely reported. Herein, two lasing modes are demonstrated in the all-inorganic perovskite CsPb2Br5 microplates with subwavelength thickness and uniform square shape. The net optical gain is quickly established in less than 1 ps and persists more than 30 ps, revealed by ultrafast transient absorption spectroscopy. The temperature-dependent low-threshold amplified spontaneous emission confirms the net gain for stimulated emission with a high characteristic temperature of 403 K, far surpassing the all-inorganic CsPbBr3 semiconductor gain media. Remarkably, upconversion lasing based on two kinds of microcavity effects, Fabry–Pérot and whispering-gallery modes, from the microplates at room temperature is successfully achieved with a low threshold operating in multi- or single-mode, respectively. Surprisingly, the quality factor (～3551) is among the best values obtained from perovskite micro/nanoplate upconversion lasers without an external cavity. Moreover, the highly stable chromaticity with color drift only less than 0.1 nm also outbalances the all-inorganic CsPbBr3 ones. These superior performances of CsPb2Br5 microplate lasing with a facile solution synthesis procedure will offer a feasible structure to fabricate specific functionalities for high-performance frequency upconversion micro/nanoscale photonic integrated devices.

Unlike organic–inorganic hybrid perovskites, all-inorganic cesium lead halide perovskites hold great promise for developing high-performance optoelectronic devices, owing to their improved stability. Herein, we investigate the perovskite-related CsPb2Br5 nanoplatelets (NPLs) with tunable emission wavelengths via changing the reaction temperatures to 100°C, 120°C, and 140°C. Reaction temperature plays a key role in determining the shapes and thicknesses of the resulting CsPb2Br5 NPLs. A higher temperature is in favor of the formation of smaller and thicker NPLs. To develop their potential applications in optoelectronic devices, green light emitting diodes (LEDs) and photodetectors based on CsPb2Br5 NPLs are fabricated. The green LEDs based on CsPb2Br5 NPLs synthesized at 140°C exhibit an excellent pure green emission (full width at half-maximum of <20 nm) and display a luminous efficiency of 34.49 lm/W under an operation current of 10 mA. Moreover, the photodetector based on CsPb2Br5 NPLs synthesized at 100°C has better performance with a rise time of 0.426 s, a decay time of 0.422 s, and a ratio of the current (with and without irradiation) of 364%.