Atomic force microscopy investigation of a step generation and bunching on the (100) facet of a CH ₃3 NH ₃3 PbI ₃3 crystal, grown from γ‐Butyrolactone

摘要

> Single crystal of organolead trihalide perovskite (CH ₃ NH ₃ PbI ₃ ) is proved to be one of the most promising semiconductor materials. Growing large size and high quality CH ₃ NH ₃ PbI ₃ single crystals is urgently demanded by photoelectric device applications. However, the growth mechanism in microscopic scale for CH ₃ NH ₃ PbI ₃ single crystal is still unrevealed. In this paper, we are focusing on observing surface structures on (100) facet of CH ₃ NH ₃ PbI ₃ single crystal via atomic force microscopy (AFM), especially surface structure conversion related to growth kinetics. The results reveal that the growth of (100) facet of CH ₃ NH ₃ PbI ₃ single crystal is dependent on bunching steps and step slope. The elemental steps, with step height about 0.45 nm, corresponded to half of the unit cell, are generated from screw dislocations when the growth rate is about 0.2 mm per hour. Elemental steps can bunch together and form bunching steps with growth rate of 0.5 mm per hour, in which only even numbers elementary steps are involved, suggesting even numbers elementary steps are stable than that of odd numbers. Additionally, in terms of the surface structures and solution stabilities, large size and high quality CH ₃ NH ₃ PbI ₃ single crystals were grown.