Hybrid organic-inorganic lead halide perovskites have emerged as promising photovoltaic materials with the best solar cell efficiency over 25%. Dimensional reduction of 3D metal halides to 2D, 1D, and 0D further leads to the discovery of many highly efficient luminescent materials with photoluminescence quantum efficiency close to 100%. In this talk, I will discuss electronic, dielectric, and defect properties that are responsible for the efficient carrier transport in hybrid halide perovskites as well as the microscopic origin of the efficient luminescence in low-dimensional metal halides based on hybrid density functional calculations of both the ground- and excited-state properties. The ΔSCF method combined with the hybrid functional are used to probe the complex excited-state energy landscape of low-dimensional metal halides, leading to the discovery of multiple self-trapped excitons in several compounds. Calculated emission energies of self-trapped excitons agree very well with experimental results and explain the optical emission trends observed in low-dimensional metal halides.

Dimensional deduction in metal halides: From photovoltaic to luminescent materials

ACS Fall 2021

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