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arXiv · 1711.08938

A New Perspective on the Role of A-site Cation in Perovskite Solar Cells

Chang Woo Myung·Jeonghun Yun·Geunsik Lee·Kwang S. Kim
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Abstract

As the race towards higher efficiency for inorganic/organic hybrid perovskite solar cells (PSCs) is becoming highly competitive, a design scheme to maximize carrier transport towards higher power efficiency has been urgently demanded. Here, we unravel a hidden role of A-site cation of PSCs in carrier transport which has been largely neglected, i.e., tuning the Frohlich electron-phonon (e-ph) coupling of longitudinal optical (LO) phonon by A-site cations. The key for steering Frohlich polaron is to control the interaction strength and the number of proton (or lithium) coordination to halide ion. The coordination to I alleviates electron-phonon scattering by either decreasing the Born effective charge or absorbing the LO motion of I. This novel principle discloses lower electron-phonon coupling by several promising organic cations including hydroxyl-ammonium cation (NH$_3$OH$^+$) and possibly Li$^+$ solvating methylamine (Li$^+$NH$_2$CH$_3$) than methyl-ammonium cation. A new perspective on the role of A-site cation could help in improving power efficiency and accelerating the application of PSCs.

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Chang Woo Myung, Jeonghun Yun, Geunsik Lee, Kwang S. Kim. 2017-11-24. A New Perspective on the Role of A-site Cation in Perovskite Solar Cells. https://doi.org/10.1002/aenm.201702898

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