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Perovskite quantum dots (QDs), such as all-inorganic CsPbX 3 (X = Cl, Br, and I), are novel fluorescent semiconductor nanocrystals (NCs) that have attracted tremendous attention due to their excellent optical properties and great applications (e.g. display backlights, light-emitting diodes, and photodetectors). The instability and toxicity of lead-based perovskite QDs, however, are intrinsic defects that obstruct their application and commercialization. Poison is released from the lead of the unstable CsPbX 3 NCs, which are generally ascribed to the labile surface, ionic character, and metastable structure. In this work, lead-free Cs 2 SnCl 6 perovskite NCs are successfully synthesized via hot injection. Particularly, by controlling the different precursor ratios, phase transition (CsCl to Cs 2 SnCl 6 ) was clearly observed from X-ray diffraction (XRD) measurements. The Cs 2 SnCl 6 NCs exhibited a highly efficient deep-blue emission at 425 nm, with a 55 nm Stokes shift and an 84 nm full width at half maximum (FWHM). After doping Mn ions, the preferred formation of CsSnCl 3 :Mn 2+ with double-wavelength emission was demonstrated based on the XRD and photoluminescence spectra. The study showed that doping synthesis should be widely used in lead-free perovskite NCs as an important strategy for next-generation solid-state lighting.

New D-π-A configured organic sensitizers featuring halogen-substituted oxindole-bridged acceptor units have been synthesized for dye-sensitized solar cells applications. Among fluorine, bromine, and iodine substitution, the cell based on bromine incorporated dye exhibited the highest efficiency. The oxindoles in these sensitizers were found to assist the electron injection through the chelation of their amide carbonyl groups to the TiO2 surface. This study provides an alternate approach for future rational dye design to gain excellent DSSC performance.

The microstructure design of TiO 2 nanoparticles for photoanodes is an important issue in optimization of dye-sensitized solar cell (DSSC) performance. Up to date, the nanostructured TiO 2 particles have been extensively employed as active layers. However, less attention has been focused on the development of various TiO 2 nanostructures as the light-scattering layers (LSLs). In the present work, a facile hydrothermal method was utilized to prepare quasi-cube TiO 2 (qcTiO 2 ) nanoparticles as the LSL for the DSSC photoanode. The anatase qcTiO 2 nanoparticles had a size distribution of 30–60 nm. The photoconversion efficiency of the cell with the qcTiO 2 LSL was enhanced 12 %, compared to the TiO 2 film without a scattering layer. The above enhancement was further vindicated by the incident photon-to-current efficiency measurement. The effect of the qcTiO 2 LSL on electron transport and charge recombination of the DSSC was studied by electrochemical impedance spectroscopy. The experiment results revealed that the enhanced photovoltaic performance is attributed to the better light-harvesting capacity, longer electron life time, and less charge recombination of the qcTiO 2 nanoparticles.

The application of freestanding TiO 2 nanotubes on the photovoltaic performance of dye-sensitized solar cells utilizing front side illumination has been investigated. TiO 2 nanotubes were grown on Ti foil using the anodization process at a constant voltage of 60 V for various anodization times such as 2, 4, and 6 h. Subsequently, the formations of freestanding films of close-ended and open-ended TiO 2 nanotubes were carried out via a second anodization step at 40 and 80 V, respectively. X-ray diffraction analysis revealed the formation of amorphous structure TiO 2 nanotubes before annealing and anatase phase after annealing at 450 °C. The diameter (60–90-nm-inner diameter) and thickness (7–19 μm) of TiO 2 nanotubes were measured from scanning electron microscopy and transmission electron microscopy analysis. The detached TiO 2 nanotube films were affixed on FTO substrates employing anatase TiO 2 paste. The fixation of freestanding TiO 2 nanotubes on FTO substrates can be categorized as three parts namely: close-ended nanotubes downside, close-ended nanotubes upside, and open-ended nanotubes. Among the various anodization times, the cells fabricated using 6 h anodized TiO 2 nanotubes photoelectrode attained excellent photoelectric efficiencies of 6.91, 6.47, and 7.69 % for close-ended downside, close-ended upside and open ended, respectively. The DSSCs based on open-ended photoelectrodes achieved the highest photoelectrical conversion efficiency are due to higher dye loading amount.

Dye‐sensitized solar cells (DSSCs) based on a TiO 2 photoanode have been considered as an alternative source in the field of renewable energy resources. In DSSCs, photoanode plays a key role to achieve excellent photo‐to‐electric conversion efficiency. The surface morphology, surface area, TiO 2 crystal phase, and the dispersion of TiO 2 nanoparticles are the most important factors influencing the properties of a photoanode. The smooth TiO 2 surface morphology of the photoanode indicates closely packed arrangement of TiO 2 particles which enhance the light harvesting efficiency of the cell. In this paper, a smooth TiO 2 photoanode has been successfully prepared using a well‐dispersed anatase TiO 2 nanosol via a simple hydrothermal process. The above TiO 2 photoanode was then compared with the photoanode made from commercial TiO 2 nanoparticle pastes. The morphological and structural analyses of both the aforementioned photoanodes were comprehensively characterized by scanning electron microscopy and X‐ray diffraction analysis. The DSSC fabricated by using a‐TiO 2 nanosol‐based photoelectrode exhibited an overall light conversion efficiency of 7.20% and a short‐circuit current density of 13.34 mA cm −2 , which was significantly higher than those of the DSSCs with the TiO 2 nanoparticles‐based electrodes.

The funnel glass of the CRT monitor contains about 22–28% of lead oxide, of which lead is a highly toxic species and hazardous to the environment. This study proposes a process to form a protective layer of SiO[sub.2] film coating on the funnel glass to reduce the hazardous effect of lead leaching to the environment. The film coating benefits from the advantages of the sol–gel method. There are two key procedures of the stabilization technique, including the alkaline treatment and the formation of SiO[sub.2] coating from TEOS. The results show that the funnel glass powder treated with 10 M NaOH can produce a mushy layer on the surface. The mushy layer, which comprises OH[sup.−] and water, can promote the formation of the SiO[sub.2] film layer on the surface of funnel glass powder. The conditions of the SiO[sub.2] film coating proposed in this study are: alkaline treatment by 10 M NaOH, the addition ratio of TEOS and funnel glass powder 2: 1, reaction temperature 40 °C, and reaction time 1.3 h. The EDS and ESCA results show that the Pb peak intensity on the surface of funnel glass decreases with the film coating. In the TCLP test, the leaching amount for Pb of the SiO[sub.2] film coated funnel glass powders is 0.7 mg/L, which is far lower than the standard in Taiwan EPA. Based on the experimental results, the formation mechanism of the SiO[sub.2] film layer on the surface of waste funnel glass powder is proposed. This study demonstrates that the SiO[sub.2] film coating is a potentially effective method to solve the problem of the waste funnel glass.

Nano-porous TiO 2 thin films have been widely used as the working electrodes in dye-sensitized solar cells (DSSCs). In this work, the phase-pure anatase TiO 2 (a- TiO 2 ) and rutile TiO 2 (r- TiO 2 ) have been prepared using hydrothermal processes. The investigation of photo-to-electron conversion efficiency of DSSCs fabricated from mixed- TiO 2 with a- TiO 2 and r- TiO 2 ratio of 80 : 20 (A8R2) was performed and compared to that from commercial TiO 2 (DP-25). The results showed higher efficiency of DSSC for A8R2 cells with same dependence of cell efficiency on the film thickness for both A8R2 and DP-25 cells. The best efficiency obtained in this work is 5.2% from A8R2 cell with TiO 2 film thickness of 12.0  μ m . The correlation between the TiO 2 films thickness and photoelectron chemical properties of DSSCs fabricated from A8R2 and DP-25 was compared and discussed.

Pure rutile-phase TiO 2 (r-TiO 2 ) was synthesized by a simple one pot experiment under hydrothermal condition using titanium (IV) n-butoxide as a Ti-precursor and HCl as a peptizer. The TiO 2 products were characterized by XRD, TEM, ESCA, and BET surface area measurement. The r-TiO 2 were rodlike in shape with average size of  nm at hydrothermal temperature of 220°C for 10 h. Hydrothermal treatment at longer reaction time increased the tendency of crystal growth and also decreased the BET surface area. The degradation of methylene blue was selected as a test reaction to confer the photocatalytic activity of as-obtained r-TiO 2 . The results showed a strong correlation between the structure evolution, particle size, and photocatalytic performance of r-TiO 2 . Furthermore, the r-TiO 2 -based solar cell was prepared for the photovoltaic characteristics study, and the best efficiency of ~3.16% was obtained.

The research achievements of a university chemistry lab regarding dye-sensitized solar cells (DSSCs) were transformed into a high school hands-on course by simplifying the experimental steps and equipment. Our research methodology was action research. We verified the DSSC course step by step. First, 10 members of a high school science study club helped to revise the course over a school semester. A questionnaire survey revealed that all students agreed that the course increased their understanding of DSSCs and solar cells. Second, 35 students were enrolled in a 10th-grade elective energy course to study the revised DSSC topics for 3 weeks. A five-point Likert scale was used to collect students’ feedback, and students reported looking forward to making their own high-performance DSSC modules (4.60) and stated that being able to make their own solar cell was a great accomplishment (4.49). Third, the course was implemented at a junior high school science camp, and the 37 participating students were all able to complete the hands-on experiment. In the questionnaire survey, the students expressed that they enjoyed learning about scientific principles through a hands-on approach (4.59). Fourth, most of the 12 schoolteachers who voluntarily participated in the DSSC workshop agreed that integrating DSSC activity into school courses would be conducive to multidisciplinary learning. This course could facilitate participants’ self-evaluations in science knowledge, experimental skills, learning motivations, and positive attitudes toward sustainability.