RESUMO
I-III-VI2 group quantum dots (QDs) have attracted high attention in photoelectronic conversion applications, especially for QD-sensitized solar cells (QDSSCs). This group of QDs has become the mainstream light-harvesting material in QDSSCs due to the ability to tune their electronic properties through size, shape, and composition and the ability to assemble the nanocrystals on the surface of TiO2. Moreover, these nanocrystals can be produced relatively easily via cost-effective solution-based synthetic methods and are composed of low-toxicity elements, which favors their integration into the market. This review describes the methods developed to prepare I-III-VI2 QDs (AgInS2 and CuInS2 were excluded) and control their optoelectronic properties to favor their integration into QDSSCs. Strategies developed to broaden the optoelectronic response and decrease the surface-defect states of QDs in order to promote the fast electron injection from QDs into TiO2 and achieve highly efficient QDSSCs will be described. Results show that heterostructures obtained after the sensitization of TiO2 with I-III-VI2 QDs could outperform those of other QDSSCs. The highest power-conversion efficiency (15.2%) was obtained for quinary Cu-In-Zn-Se-S QDs, along with a short-circuit density (JSC) of 26.30 mA·cm-2, an open-circuit voltage (VOC) of 802 mV and a fill factor (FF) of 71%.
RESUMO
The development of photo-responsive nanocomposite materials is important in the fabrication of optoelectronic devices. In this work, we fabricated a carbon dot doped azobenzene-clay nanocomposite which possesses different ac conductivity with and without UV treatment. At first, azobenzene nanoclusters were synthesised and then successfully used to make an azobenzene-clay nanocomposite. It was observed that there is a small change in the ac conductivity of the azobenzene-clay nanocomposite with and without UV treatment. However, this change in ac photoconductivity can be enhanced in the azobenzene-clay nanocomposite by doping with electron-rich cysteine and methionine carbon dots. Hence, ac conductivity properties of the carbon-doped azobenzene-clay nanocomposite can be tuned using UV light. Impedance measurements were determined using Electrochemical Impedance Spectroscopy. Mechanistic insight into the phenomenon is also discussed in the paper. Thus fabrication of tunable carbon dot doped photo-responsive azobenzene-clay nanocomposites will lead to the use of carbon dot doped azobenzene-clay nanocomposites in photo-switchable optoelectronic devices.
