Orange emissive carbon dots with 82% PL quantum yield and 30 nm full width at half maximum are utilized as a laser gain medium to realize whispering gallery mode solid state lasers for the first time.

Random lasing is achieved from carbon dot fibers. Tunability of the lasing wavelength and threshold, which are key to achieving multilevel anti-counterfeiting, is realized by controlling the thermal decomposition time and fiber diameter.

Carbon dots (CDs), a subject of academic research, have attracted intense attention due to their intrinsic merits of high stability, low cost, and low toxicity. However, the absence of highly...

The use of organosilane chains to link carbon nanodots (CDs) through organosilane surface functional groups is proposed to improve the efficiency of multiphoton absorption. As a result, a large absorption coefficient of 1.16 × 10 cm per GW is obtained and four-photon luminescence under 1900 nm excitation is observed from the CDs at room temperature. Furthermore, a CD laser, which demonstrates random lasing under three-photon (i.e. 1400 nm) excitation, can be realized by sandwiching a CD film between a quartz substrate and a dielectric mirror. The formation of strongly confined microcavities, which arise from the non-uniform distribution of refractive indices inside the CD film, is attributed to the realization of lasing emission.

The absence of an ideal solid matrix with resistance to harsh conditions for carbon dots (CDs) and high transmittance in the visible/near infrared region is the bottleneck in CD applications. In this study, we show that a stable rigid structure can be formed between CDs and organically modified silicates (ormosil) gel when CDs are incorporated into ormosil gel hybrids as a solid matrix. A high photoluminescence quantum yield (PLQY) of 63% is achieved at a 583 nm emission. Peak optical gain of the hybrids was found to be 67 cm−1 at peak wavelength. Ultralow threshold (~70 W/cm2) lasing can also be demonstrated from a planar microcavity by using CD–ormosil gel hybrids as a gain medium.

No abstract

Due to the excellent properties of wide band gap, high bulk carrier mobility, and suitable band alignment with a perovskite layer, tin dioxide SnO2 is an outstanding candidate as an electron transport layer (ETL) for perovskite solar cells (PSCs). However, it is still desirable and challenging to deposit crystalline SnO2 thin films by the low-temperature solution process. By adjusting the metal-halide chemical bonding strength of a tin precursor, thus controlling the hydrolysis intermediate species, we demonstrated a simple method for preparing high-quality SnO2 thin films. This method is free of organic surfactants and the formation of tin-alkoxide intermediates. Consequently, SnO2 thin films with high crystallinity and high-carrier-mobility can be obtained under low temperature. This crystalline SnO2 ETL enables efficient charge separation/transport and reduces charge recombination in PSCs. Moreover, the Br-rich perovskite region is established near the SnO2/perovskite interface, resulting in a beneficial gradient band gap profile in the device. PSCs with this SnO2 ETL show a PCE of over 22% with an outstandingly high fill factor of 83.32%.

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) quantum dots (QDs) are the vanguard due to their unique properties. In this work, WSe2 QDs were fabricated via one step ultrasonic probe sonication. Excitation wavelength dependent photoluminescence (PL) is observed from WSe2 QDs. Room-temperature lasing emission which benefits from 3.7 times enhancement of PL intensity by thermal treatment at ~470 nm was achieved with an excitation threshold value of ~3.5 kW/cm2 in a Fabry–Perot laser cavity. To the best of our knowledge, this is the first demonstration of lasing emission from TMDCs QDs. This indicates that TMDCs QDs are a superior candidate as a new type of laser gain medium.