Electrical transport properties of TiO2/MAPbI3 and SnO2/MAPbI3 heterojunction interfaces under high pressure.

The electrical transport properties of SnO2(TiO2)/MAPbI3 (MA = CH3NH3 +) heterojunction interfaces are investigated from ambient pressure to 20 GPa, and the transport properties are calculated by physical parameters such as trap energy density, binding energy, and charge transfer driving force and defect. Based on the partial density of states (PDOS) of the SnO2/MAPbI3 heterojunction interface MAI-termination and PbI2-termination, greater charge transfer driving force and higher binding energy are observed, obviously showing the SnO2-based heterojunction is more stable. The SnO2/MAPbI3 heterojunction interface possesses stronger electrical transport ability and is less prone to capture electrons compared with the TiO2/MAPbI3 heterojunction interface. The differential charge density spectrum shows that the density is lower in the trap energy level of SnO2/MAPbI3, whilst the effect of the charge transfer defect is weaker owing to the trap energy level only existing in SnO2. The SnO2/MAPbI3 heterostructure interface is less prone to capture electrons. The greater electron concentration difference is attributed to oxygen vacancy (Vo0) in the SnO-like environment, resulting in superior electron transport ability compared with the TiO-like environment.

Novel single component tri-rare-earth emitting MOF for warm white light LEDs.

Single-phase white phosphors could overcome many drawbacks of traditional phosphors, and warm white light phosphors have been considered suitable for indoor illumination applications. Thus, synthesizing new single-phase warm white phosphors is significant for the production of LEDs. Based on the above considerations, a novel single component warm white light phosphor SmxTbyDy0.2-x-y-metal organic frameworks (MOFs) has been prepared successfully in this study. The compound Sm0.1Tb0.04Dy0.06-MOF shows ideal warm white light emission with CIE coordinates (0.333, 0.3522), a color rendering index (CRI) value of 86.7, a low correlated color temperature (CCT) value of 4444 K, and good heating/cooling circulation. In addition, the LED devices fabricated with this novel warm white light phosphor have excellent warm white light quality even at high temperatures, which is necessary for its practical application.