This work demonstrates a pathway for the large-scale design of novel organic–inorganic functional materials in a high-throughput fashion.

Compared with their three-dimensional counterparts, low-dimensional metal halide perovskites with periodic inorganic/organic structures have shown promising stability and hysteresis-free electrical performance, which paves the way for next-generation optoelectronic devices. However, when integrated in devices, they have relatively limited efficiencies because devices usually require carrier transport through the film thickness direction. In conventionally grown single crystals, the carrier transport in the thickness direction is hindered by the insulating organic spacers. In addition, the strong quantum confinement from the organic spacers limits the generation and transport of free carriers. The carrier dynamics is further compromised by the presence of grain boundaries in polycrystals. Here, we report a low-dimensional metal halide perovskite superlattice with efficient carrier transport in three dimensions by epitaxial growth. Epitaxy on a slightly lattice-mismatched substrate compresses the organic spacers in the superlattice, which weakens the quantum confinement and further improves carrier dynamics. The performance of a low-dimensional perovskite superlattice solar cell has been certified under the quasi-steady state for the first time. Moreover, the device shows an unusually high open-circuit voltage, due to a unique intra-band exciton relaxation mechanism.

Organic–inorganic hybrid perovskites with a prototype formula MAPbI3 (MA = CH3NH3) have shown great promise in next-generation solar cells, yet a full understanding of their high power conversion efficiency relative to their inorganic counterparts has not been achieved. One of the most plausible arguments for their high efficiency is the ability of organic cations to form ferroelectric (FE) domains. By using first-principles calculations to examine the rotational behavior of MA cations in MAPbI3, here we show a relationship between the lattice structures and the FE dipole ordering of MA cations. It is found that the MA cations could form a spontaneous FE dipole ordering in tetragonal MAPbI3 at room temperature. The tendency of the FE formation is strongly related to the ratio of lattice parameters of MAPbI3. On the basis of the developed structure–ferroelectric-property relationship, we propose that a biaxial or uniaxial compressive strain and an anion doping with small halogen ions can further enhance the FE dipole ordering. These findings are in good agreement with the experimental discoveries that high-performance solar cells always incorporate mixed halide hybrid perovskites involving Br or Cl ions. This work may provide some guidelines for rational designs of highly efficient hybrid perovskite solar cells.

On the basis of the screened 29 hybrid halide compounds from our prior study [Y. Li and K. Yang, Energy Environ. Sci. 12, 2233–2243 (2019)], here, we reported a systematic computational study of the stability diagram, defect tolerance, and optical absorption coefficients for these candidate materials using high-throughput first-principles calculations. We took two exemplary compounds, MA2SnI4 and MA3Sb2I9, as examples to show the computational process, and they are discussed in detail. This work is expected to provide a detailed guide for further experimental synthesis and characterization, with the potential to develop novel lead-free optoelectronic devices.