Organic-inorganic hybrid perovskite compounds based on metal halides with ABX3 chemical formula have recently attracted a tremendous amount of attention in the optoelectronic community. This perovskite structure consists of a network of corner-sharing BX6 octahedra to influence the valence and conduction band energies and orbital composition and hence the stability of electrons and holes in the material, where the B atom is a metal cation (typically a divalent group-IVA cation Pb2+ or Sn2+) and the X is halide or their mixture. And the A cation is a small monovalent organic ion-typically methylammonium (CH3NH3+, MA+) or formamidinium (HC(NH2)2+, FA+) to balance the total charge and it can even be a caesium (Cs+) or a small molecular species. Although the rich versatility in perovskite materials and the diversity in device architectures promise an inviting vista of commercialization, the vulnerability to moisture, air, heat, or prolonged exposure to sunlight has slowed the development process, preventing them from scaling new heights in efficiency and practical applications. To enhance the device stability, intensive investigation on encapsulation, alternative corrosion-resistive metal electrodes or doping free charge transport layers have been explored. In this talk, we shall present our recent work on tuning strain via appropriate lattice constriction within BX6 octahedra, employing the Zn for example-substitution as prototype from theoretical simulation and experimental verification to explore the formation of ordered perovskite and its inherent influence on photoelectric properties.[1,2] This is expected to have important practical consequences as the need for further improving perovskite thin film quality and device performance by understanding substitution effect and crystal features. Work is in progress to further improve the performance of this promising system by optimizing the crystal structure and composition forms of this novel perovskite compounds and charge selective layers.

Pb-less perovskite solar cells

2019 Spring National Meeting

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