ABSTRACT
K2CuBr3 single crystals (SCs) are synthesized using a cooling-induced crystallization method with violet emission due to self-trapped excitons (STEs) under photoexcitation. The prepared K2CuBr3 SCs exhibit a high photoluminescence quantum yield (PLQY, 79.2%) and excellent stability against moisture, heat and UV light. When the K2CuBr3 SCs are used as a light source for visible light communication the data transmission rate reaches a striking 248 Mbps, which is more than 33-fold the -3 dB bandwidth.
ABSTRACT
In this work, we report a novel, to the best of our knowledge, strategy to improve the performance of UV-Vis self-powered CsPbBr3 quantum dot (QD) based photodetectors (PDs) by ligand modification and poly(3-hexylthiophene) (P3HT) embedding. Compared with those based on pure QDs, modified PDs show a shortened response time by nearly ten times, and increases of maximum responsivity and specific detectivity by nearly 45 and 97 times, respectively. Such PDs also show a high stability with 90% of the initial photocurrent being maintained even after storage in ambient air without any encapsulation for 30 days.
ABSTRACT
With a high photoluminescence quantum yield (PLQY) being able to exceed 90% for those prepared by the hot injection method, CsPbBr3 quantum dots (QDs) have attracted intensive attention for white light-emitting diodes (WLEDs). However, the whole process is carried out in a 3-neck flask via air isolation and at a relatively high temperature. In addition, CsPbBr3 QDs suffer from poor stability under ambient atmosphere. In this work, an effective strategy through doping of Sn2+ ions at room-temperature is proposed to improve the emission efficiency and stability of CsPbBr3 QDs. Compared with pure CsPbBr3 QDs, a higher PLQY and a better stability are obtained. The detailed physical mechanism for this performance enhancement is discussed and described. An optimum result is found at an Sn2+ doping amount of 20%, which shows a high PLQY of 82.77%. WLEDs based on these 20% Sn2+ doped CsPbBr3 QDs are also studied, exhibiting a high color rendering index of 89 and a correlated color temperature (CCT) of 3954. The method proposed here provides an effective strategy to enhance the fluorescence and stability of CsPbBr3 QDs, which might have promising potential in the lighting fields.
ABSTRACT
A series of N-Fe-Bi2Ti2O7 nanofibers were successfully synthesized. The structure, morphology, visible light photocatalytic properties, and the degradation mechanism of N-Fe-Bi2Ti2O7 were investigated. A new phase of Bi4Ti3O7 and smaller band gap could be observed after doing Fe and N into Bi2Ti2O7. It can degrade 66 % MO and 87 % MB in 120 min under visible light irradiation, which is much more than that of pure Bi2Ti2O7. The results indicate that such unique structure could enhance the charge transfer between the nanostructure interfaces and therefore improve its photocatalytic activities.
ABSTRACT
Novel carbon quantum dot (CQD)-modified BiOI photocatalysts were prepared via a facile hydrothermal process. The CQD-modified BiOI materials were characterized by multiple techniques. The CQD with an average size around several nanometers was distributed on the surface of BiOI microsphere. Its photocatalytic activity was investigated sufficiently by the photodegradation of methylene orange (MO). The results showed that the CQD/BiOI 1.5 wt.% sample exhibited the optimum photocatalytic activity, which was 2.5 times that of the pure BiOI. This improvement was attributed to the crucial role of CQDs, which could be acted as a photocenter for absorbing solar light, charge separation center for suppressing charge recombination.
