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This study demonstrates a broadband-tunable photonic bandgap (PBG) and thermally convertible laser with an ultra-low lasing threshold based on a gradient-pitched cholesteric liquid crystal (CLC) polymer template. The lowest energy threshold of the laser is 16 nJ per pulse under a pumped diameter of ca. 250 μm (i.e., 0.33 μJ per pulse per mm2), a value that is superior to those of other band-edge lasers based on most dye/quantum-dot-doped CLC systems. Owing to its multiple advantages, such as high stability, ultra-low lasing threshold, wide-band and linear spatial PBG-tunability, and lasing-mode convertibility, the CLC template device can be potentially used for photonics and display applications.

Dye-doped nematic liquid crystal refilled gradient-pitched enantiomorphic cholesteric liquid crystal polymer templates are demonstrated. The enantiomorphic device has high reflectivity and wide spectral tunability throughout the entire visible region. This device can also provide low threshold lasing emission with both right- and left-circular polarizations from the blue to the red region.

This study applies a low-cost solvothermal method to synthesize all-inorganic (lead-free cesium tin halide) perovskite quantum dots (AIPQDs) and to fabricate AIPQD-doped lasers with cholesteric liquid crystal (CLC) lasing cavities. The lasers present highly qualified lasing features of low threshold (150 nJ/pulse) and narrow line width (0.20 nm) that are attributed to the conjunction of the suppression of photoluminescence (PL) loss caused by the quantum confinement of AIPQDs and the amplification of PL caused by the band-edge effect of the CLC-distributed feedback resonator. In addition, the lasers possess highly flexible lasing-wavelength tuning features and a long-term stability under storage at room temperature and under high humidity given the protective role of CLC. These advantages are difficult to confer to typical light-emitting perovskite devices. Given these merits, the AIPQD-doped CLC laser device has considerable potential applications in optoelectronic and photonic devices, including lighting, displays, and lasers.

Herein, the fabrication of a lead-free cesium germanium halide perovskite produced via a simple solvothermal process is reported for the first time. By tuning the composition of the CsGeX3 quantum rods, a power conversion efficiency of 4.92% under AM 1.5 G was achieved.

This investigation is the first report of an optically stable and tunable laser using a quantum-dot (QD) embedded cholesteric liquid crystal (QD-CLC) microresonator with an added chiral-azobenzene moiety. The QD nanocrystal, CLC, and chiral-azobenzene play key roles in the highly stable fluorescence nano-emitter, microresonator, and photo-tuner in the photonic bandgap (PBG) of the CLC and associated lasing output, respectively. Experimental results show that both the PBG and lasing emission of the QD-CLC composite sample can be reversibly tuned under successive irradiation with UV and blue beams. The all-optical tunability of the laser is attributed to the successive elongation and shrinkage of the CLC pitch induced by UV- and blue beam-irradiation induced trans–cis and cis–trans back isomerizations of chiral-azobenzene, respectively. In addition, this composite laser has a high damage threshold (>85 μJ per pulse), and thus shows a uniquely high optical stability. This work has successfully opened up an opportunity for developing QD coherent light sources or lasers with good optical stability and tunability (e.g., optically stable and tunable single photon lasers).

A copolymer has been used as a template for enhanced optical properties of core–shell CdS/ZnSe quantum dots doped cholesteric liquid crystal. The lasing behavior is achieved at relatively low laser excitation energy threshold at room temperature. Low-threshold value and high-optical stability make this optical system promising for visible laser emitter applications.

The photoluminescence quantum efficiency of quantum dots (QDs) at room temperature was markedly enhanced about 2 times by surface treatment of the nanocrystals, and the original lasing emission peak position and narrow line width were maintained. We report an investigation of the impact of surface passivation on the optical properties of QDs. Thiol coating was used to passivate the surface states that the luminescence efficiency of QDs can be improved.

Quaternary kesterite-type Cu2ZnSnS4 nanowires can be used as absorbing materials for thin film solar cells. The structural, morphological, compositional, and optical properties of the CZTS nanowires have been studied using X-ray diffraction (XRD), UV–vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and optical absorption techniques respectively. The Cu2ZnSnS4 nanowires, fabricated by electrospinning process and sintered at 600 °C in Argon atmosphere, the cells exhibits a power conversion efficiency of 6.18% under AM 1.5 solar irradiation in the thin film solar cells. This study suggests that the optimized Cu2ZnSnS4 composite nanowire is a promising absorbing material for high performance solar cells.

Stannites are important contenders among thin-film solar cells due to their direct band gap and higher absorption coefficient. I 2 –II–IV–VI 4 nanocrystals of Cu 2 ZnSnSe 4 are stannite material with a near-optimum band gap of ∼1.5 eV. Semiconductor Cu 2 ZnSnSe 4 nanorods were successfully prepared via a relatively simple and convenient solvothermal route. The device parameters for a single junction Cu 2 ZnSnSe 4 solar cell under AM1.5G are as follows: open circuit voltage of 308 mV, short-circuit current of 29.9 mA/cm 2 , fill factor of 27%, and a power conversion efficiency of 2.48%. Based on a series of comparative experiments under various reaction conditions, the probable formation mechanism of crystals Cu 2 ZnSnSe 4 nanorods is proposed.

Kesterites are important contenders among thin-film solar cells due to their direct band gap and higher absorption coefficient. I 2 –II–IV–VI 4 nanocrystal of Cu 2 ZnSnS 4 is a chalcopyrite material with a near-optimum band gap of ∼1.5 eV. Semiconductor Cu 2 ZnSnS 4 nanorods were successfully prepared via a relatively simple and convenient solvothermal route. The device parameters for a single junction Cu 2 ZnSnS 4 solar cell under AM1.5G are as follows: open circuit voltage of 319 mV, short-circuit current of 25.5 mA/cm 2 , fill factor of 25, and a power conversion efficiency of 2.03%. Based on a series of comparative experiments under various reaction conditions, the probable formation mechanism of crystals Cu 2 ZnSnS 4 nanorods is proposed.

Herein, the fabrication of a lead-free cesium tin halide perovskite produced via a simple solvothermal process is reported for the first time. The resulting CsSnX3 (X = Cl, Br, and I) quantum rods show composition-tunable photoluminescence (PL) emissions over the entire visible spectral window (from 625 to 709 nm), as well as significant tunability of the optical properties. In this study, we demonstrate that through hybrid materials (CsSnX3) with different halides, the system can be tunable in terms of PL. By replacing the halide of the CsSnX3 quantum rods, a power conversion efficiency of 12.96% under AM 1.5 G has been achieved. This lead-free quantum rod replacement has demonstrated to be an effective method to create an absorber layer that increases light harvesting and charge collection for photovoltaic applications in its perovskite phase.

Chalcopyrite Cu(In 0.8 Ga 0.2 )S 2 (CIGS) nanowires were synthesized by using a relatively simple and convenient electrospun process. From the reactions of CuCl, InCl 3, GaCl 3 and thiocarbamide as a precursor, semiconductor CIGS nanowires with diameter in the range of 60–80 nm were obtained for Polyvinylbutyral/CIGS precursor ratios of 40% at an applied voltage of 25 kV after annealing treatment at 600 °C for 3 h. A probable formation mechanism of chalcopyrite quaternary semiconductor nanowires is proposed based on a series of comparative experiments conducted under various reaction conditions.

This study demonstrates for the first time a continuously tunable photonic bandgap (PBG) of wide spectral range based on a blue phase (BP) wedge cell. A continuously shifting PBG of the BP wedge cell occurs due to the thickness gradient of the wedge cell at a fixed temperature. The wedge cell provides a gradient of boundary force on the LCs and thus forms a distribution of BP crystal structure with a gradient lattice. Additionally, a spatially tunable lasing emission based on a dye-doped BP (DDBP) wedge cell is also demonstrated. The tunable band of the PBG and lasing emission is about 130 nm and 70 nm, respectively, which tuning spectral ranges are significantly wider than those of CLC and DDCLC wedge cells, respectively. Such a BP device has a significant potential in applications of tunable photonic devices and displays.

This work reports, for the first time, a dielectrophoresis (DEP) effect-induced motion of liquid crystal (LC) droplets in an LC/monomer mixture sample with a poly-(N-vinyl carbazole) PVK-coated substrate without an external voltage. With the UV pre-irradiation of the PVK layer through a binary mask, a laterally non-uniform electric field can be induced between the pre-illuminated regions and the neighboring non-pre-illuminated PVK regions near the borders of the two regions. The phase separation occurs once the temperature is lower than 50 °C and the LC droplets can form in the sample. The pre-formed non-uniform field provides a DEP-like force to manipulate the small LC microdroplets in the pre-illuminated regions to effectively migrate to the adjacent non-pre-illuminated regions. The continuous supply of the LC from the pre-illuminated regions to the adjacent non-pre-illuminated regions significantly increases the diffraction efficiency of the grating sample. This study provides an insight into developing new external-voltage-free DEP-based devices that can be applied on various fields, such as photonics, displays, and biomedicines.

This study systematically investigates the morphological appearance of azo-chiral dye-doped cholesteric liquid crystal (DDCLC)/polymer coaxial microfibers obtained through the coaxial electrospinning technique and examines, for the first time, their photocontrollable reflection characteristics. Experimental results show that the quasi-continuous electrospun microfibers can be successfully fabricated at a high polymer concentration of 17.5 wt% and an optimum ratio of 2 for the feeding rates of sheath to core materials at 25 °C and a high humidity of 50% ± 2% in the spinning chamber. Furthermore, the optical controllability of the reflective features for the electrospun fibers is studied in detail by changing the concentration of the azo-chiral dopant in the core material, the UV irradiation intensity, and the core diameter of the fibers. Relevant mechanisms are addressed to explain the optical-control behaviors of the DDCLC coaxial fibers. Considering the results, optically controllable DDCLC coaxial microfibers present potential applications in UV microsensors and wearable smart textiles or swabs.

Cu(In0.9B0.1)Se2 nanocrystals are solvothermally synthesized from a stoichiometric mixture of Se, CuCl, InCl3, and B2O3 in diethylenetriamine (autoclave, 180 °C, 36 h).

Chalcopyrite quaternary semiconductor Cu(In(x)B(1-x))Se(2) nanocrystals have been successfully prepared via a relatively simple and convenient solvothermal route. The effect of different solvents on the formation of the product also indicates that diethylenetriamine is the optimal solvent for this reaction. The device parameters for a single junction Cu(In(x)B(1-x))Se(2) solar cell under AM1.5G are as follows: an open circuit voltage of 265 mV, a short-circuit current of 25.90 mA/cm(2), a fill factor of 34%, and a power conversion efficiency of 2.34%. Based on a series of comparative experiments under different reaction conditions, the probable formation mechanism of crystal Cu(In(x)B(1-x))Se(2) nanorods is proposed.

Correction for ‘Surface passivation assisted lasing emission in the quantum dots doped cholesteric liquid crystal resonating cavity with polymer template’ by Lin-Jer Chen et al., RSC Adv., 2014, 4, 52804–52807.

Chalcopyrites are important contenders among thin-film solar cells due to their direct band gap and higher absorption coefficient. Copper–boron–selenium (CuBSe2) is a chalcopyrite material with a near-optimum band gap of ∼3.13 eV. Semiconductor CuBSe2 nanorods were successfully prepared via a relatively simple and convenient solvothermal route. The device parameters for a single junction CuBSe2 solar cell under AM 1.5 G are as follows: open circuit voltage of 310 mV, short-circuit current of 25.5 mA cm−2, fill factor of 24%, and a power conversion efficiency of 1.89%. Based on a series of comparative experiments under various reaction conditions, the probable formation mechanism of crystals CuBSe2 nanorods is proposed.

This study shows an increase in LAA flow after PTMV in both normal sinus rhythm and atrial fibrillation. These results suggest that relief of mitral stenosis may not only confer hemodynamic benefits for the improvement of symptoms but also have a favorable influence on future thromboembolism.