Electrochemiluminescence (ECL) has established itself as an excellent transduction technique in biosensing and light-emitting device, while conventional ECL mechanism depending on spontaneous emission of luminophores lacks reversibility and tunable emission characters, limiting the universality of ECL technique in the fields of fundamental research and clinical applications. Here, we report the first observation of stimulated emission route in ECL and thus establish a reversible tuning ECL microscopy for single-cell imaging. This microscopy uses a focused red-shifted beam to transfer spontaneous ECL into stimulated ECL, which enables selective and reversible tuning of ECL emission from homogeneous solution, single particles, and single cells. After excluding other possible competitive routes, the stimulated ECL emission route is confirmed by a dual-objective system in which the suppressed spontaneous ECL is accompanied by the enhanced stimulated ECL. By incorporating a commercial donut-shaped beam, the sharpness of single-cell matrix adhesion is improved 2 to 3 times compared with the counterpart in confocal ECL mode. The successful establishment of this stimulated emission ECL will greatly advance the development of light-emitting device and super-resolution ECL microscopy.
Single crystal metal halide perovskites thin films are considered to be a promising optical, optoelectronic materials with extraordinary performance due to their low defect densities. However, it is still difficult to achieve large-scale perovskite single-crystal thin films (SCTFs) with tunable bandgap by vapor-phase deposition method. Herein, the synthesis of CsPbCl 3(1– x ) Br 3 x SCTFs with centimeter size (1 cm × 1 cm) via vapor-phase deposition is reported. The Br composition of CsPbCl 3(1– x ) Br 3 x SCTFs can be gradually tuned from x = 0 to x = 1, leading the corresponding bandgap to change from 2.29 to 2.91 eV. Additionally, an low-threshold (≈23.9 µJ cm −2 ) amplified spontaneous emission is achieved based on CsPbCl 3(1– x ) Br 3 x SCTFs at room temperature, and the wavelength is tuned from 432 to 547 nm by varying the Cl/Br ratio. Importantly, the high-quality CsPbCl 3(1– x ) Br 3 x SCTFs are ideal optical gain medium with high gain up to 1369.8 ± 101.2 cm −1 . This study not only provides a versatile method to fabricate high quality CsPbCl 3(1– x ) Br 3 x SCTFs with different Cl/Br ratio, but also paves the way for further research of color-tunable perovskite lasing.
Liquid-state optical gain media are desired for high-power lasing applications due to their easier heat management than solid-state media, as well as for the emerging field of optofluidics. Colloidal quantum dots (QDs) are solution-processed materials that carry many attractive properties suitable for liquid lasing. To date, however, their lasing action is often achieved in close-packed films, as a high volume fraction of QDs is required for stimulated emission to outpace the ultrafast Auger decay of gain-active multiexciton states. Here we report liquid lasing from color-tunable (red, orange, and green) alloyed core/shell QDs with impeded Auger recombination. Lasing action is achieved by loading the QD-solutions into cavities under quasi-continuous-wave excitation. The light amplification behaviors of QD-solutions under ambient conditions are much more stable compared to those of both solid-state QD-films and dye solutions. Compatibility with aqueous solvents and ease of scalability are also demonstrated. An optimized optical power efficiency of 17.2% has been achieved. These results indicate that liquid lasing from colloidal QDs holds strong promise for real-world implementation.
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