The thermal decomposition products and kinetics of two typical organic−inorganic halide perovskites, CH 3 NH 3 PbI 3 (MAPbI 3 ) and HC(NH 2 ) 2 PbI 3 (FAPbI 3 ), were investigated via simultaneous thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. NH 3 and CH 3 I were verified as the major thermal decomposition gases of MAPbI 3 . Furthermore, for the first time, methane (CH 4 ) was observed as a thermal degradation product of MAPbI 3 at elevated temperatures. In contrast to conventional wisdom, (HCN) 3 (trimerized HCN) and NH 3 were demonstrated as the major gaseous decomposition products of FAPbI 3 at lower temperatures, while HCN and NH 3 became dominant at high temperatures (>360 °C). The hybrid experimental/theoretical results presented in this study will further our understanding of the perovskite decomposition mechanism and provide new insights into designing of long-term stable perovskite-based devices.

Transparent glass ceramics containing Ce 3+ -Yb 3+ codoped Y 3 Al 5 O 12 nanocrystals were prepared, and their microstructures were characterized by X-ray diffraction and transmission electron microscopy. Intense near-infrared emission at around 1000 nm, attributed to the 2 F 5/2 / 2 F 7/2 transition of Yb 3+ , was observed upon excitation at 452 nm. Efficient energy transfer from Ce 3+ ions to Yb 3+ ions was confirmed by the luminescence spectrum and fluorescent lifetime measurements; the mechanism was investigated and demonstrated to be a single-photon process rather than a two-photon process.Greatly enhanced near-infrared emission was achieved from the glass ceramics excited by simulated sunlight from 400 to 800 nm compared with that from as-prepared glass. These results demonstrate that the glass ceramics are promising materials for spectral conversion from visible sunlight to nearinfrared emission and may have potential applications as spectral convertors to enhance the photoelectric conversion efficiency of c-Si solar cells.

Carrier lifetime in flexible CH3NH3PbI3 films increases with increasing tensile strain, and conversely decreases with increasing compressive strain.