Yang Sheng,Shuai Li,Yixin Sun,Rong Zhang,Xinyu Zhao,Mei Chee Tan
CuInSe2 quantum dots (QDs) are one of the most important Cd-free fluorescent probes; they usually exhibited low fluorescence intensity, suggesting that a considerable amount of absorbed photon energy was lost as heat. In this study we aimed to improve the fluorescence intensity of CuInSe2 QDs and investigate their photoacoustic (PA) signal resulting from the heat dissipation, which was previously rarely reported. Cu–In–Zn–Se/ZnSe QDs were synthesized by adopting two strategies of Zn doping and ZnSe shell growth. It was found that there was an upper limit for Zn concentration beyond which the fluorescence intensity began to decrease. In addition, a blue shift of the emission peak of Cu–In–Zn–Se/ZnSe QDs was observed at high concentrations of ZnSe precursor due to the diffusion of excessive Zn. To prepare the dual-modal fluorescence and PA imaging probe, poly(maleic anhydride-alt-1-octadecene) (PMAO) modified with polyethylene glycol (PEG) was coated on the QDs, which led to a slight reduction in fluorescence. Cellular labeling on HeLa cells was performed to demonstrate the utility of these probes for fluorescence imaging. We further studied the in vitro PA imaging capabilities of the Cu–In–Zn–Se/ZnSe/PMAO-g-PEG nanoparticles, which showed a distinct PA signal beyond 1.0 mg ml−1. The current work demonstrated that a moderate amount of Zn doping is necessary for enhancing fluorescence and there is a limit beyond which the fluorescence will be diminished. We also demonstrated the proof of concept that Cu–In–Zn–Se/ZnSe QDs are able to serve as a potential PA imaging contrast agent.
“Green” narrow band-gap CuInSe2 quantum dots (QDs) were first introduced in photodetectors. Thus, a broadband hybrid photodetector was obtained by combining the ultraviolet detection of spiro-OMeTAD and the near-infrared detection of CuInSe2 QDs. In order to improve the detection of the device, the oil-soluble CuInSe2 QDs were transformed into water-soluble MPA-capped QDs through ligand exchange, which drastically shortened the length of the surface ligand. The specific detectivity (D*) of the photodetector reached 1.6 × 1012 Jones at 330 nm and 7.5 × 1010 Jones at a 1000 nm wavelength. The unencapsulated device also displayed a fast response time (<0.02 s) and excellent thermal stability (20–100 °C) in ambient air. This work could open a window of toxic-free QD based photodetectors to achieve a broadband response.
Yan Zhang,Zhenlong Zhang,Yanyan Liu,Yuefeng Liu,Huiping Gao,Yanli Mao
In this work, we synthesized CuInSe 2 quantum dots (CISe QDs) and applied them to perovskite solar cells (PSCs) as an inorganic hole-transporting material (HTM). A power conversion efficiency (PCE) of 12.8% was achieved for the PSCs using CISe QDs as the HTM, which is the highest value reported to date for devices with a Cu-based chalcopyrite semiconductor as HTM. More importantly, the stability of PSCs with CISe QDs was significantly improved compared with that of the devices using spiro-OMeTAD as the HTM. These results demonstrate that CISe QDs are a promising inorganic HTM for PSCs with long-term stability and low cost.
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