Recently, layered perovskites attracted great attention for its excellent stability and light-emitting property. However, most of them rely on the toxic element lead and their emission quantum yields are generally low. Here, a unique hollow two-dimensional perovskite was developed in which the organic hexamethylene diamines (CHN) strongly coupled with distorted tin bromide anions (SnBr). This toxic-free low-dimensional tin perovskite exhibits a broadband emission in the visible region with a high luminescence quantum yield of 86%. First-principles calculation indicate the broadband emission is associated with the recombination of self-trapped excitons. And the emission is related to the geometry of tin bromide anions. An ultraviolet light-pumped white light emitting diode with excellent color-rendering index of 94 was fabricated using it together with a commercially available blue phosphor.

The carrier lifetime and the doping property of the lead halide perovskites are essential factors determining their application in solar cells. Hence, these two factors of the perovskite (CH 3 NH 3 PbI 3 ) film were managed by postannealing, and the underlying mechanisms governing their effects on the photovoltaic performance of the solar cells were investigated. The short carrier lifetime from electron-hole bimolecular recombination, corresponding to the fast decay of photoluminescence, is achieved in perovskite films annealed at high temperatures. The doping property of the perovskite varies from p-type, intrinsic to n-type with increasing annealing temperature. The short carrier lifetime and the intrinsic feature of the perovskite benefit for high open circuit voltage of the corresponding solar cells, whereas the n-type doped perovskite leads to the high photocurrent and efficiency. Through the management of the carrier lifetime and the doping property, highly efficient perovskite solar cells with conversion efficiency over 17% were prepared. These results provide new insights into the underlying relations between the perovskite properties and the device performance.

Halide double perovskites A2B­(I)­B­(III)­X6, in which monovalent B­(I) and trivalent B­(III) cations are arranged in the B-sites of the perovskite structure with a rock-salt ordering, have attracted substantial interest in the field of optoelectronics. However, the rock-salt ordering generally leads to low electronic dimensionality, with relatively large bandgaps and large carrier effective masses. In this work, we demonstrate, by density functional theory (DFT) calculations, that the electronic dimensionality and thus the electronic properties of halide double perovskites can be effectively modulated by manipulating the arrangement of the B-site cations. Through symmetry analysis and DFT calculations, we propose a family of halide double perovskites A2B­(I)­B­(II)­X5 where the B-site cations adopt a columnar-ordered arrangement. Among the considered compounds, Cs2AgPdCl5, Cs2AgPdBr5, and Cs2AgPtCl5 were successfully synthesized as the first examples of the B-site columnar-ordered halide double perovskites. These compounds exhibit small bandgaps of 1.33–1.77 eV that are suitable for visible light absorption, small carrier effective masses along the octahedra chains, and good thermal and air stability. Our work provides a prototype double perovskite structure to incorporate cations in +1 and +2 oxidation states, which may significantly expand the large family of the halide double perovskites and offer a platform to explore prospective optoelectronic semiconductors.