posted on 2020-03-16, 16:10authored byGuoqing Tong, Maowei Jiang, Dae-Yong Son, Longbin Qiu, Zonghao Liu, Luis K. Ono, Yabing Qi
Control
of forward and inverse reactions between perovskites and
precursor materials is key to attaining high-quality perovskite materials.
Many techniques focus on synthesizing nanostructured CsPbX3 materials (e.g., nanowires) via a forward reaction (CsX + PbX2 → CsPbX3). However, low solubility of inorganic
perovskites and complex phase transition make it difficult to realize
the precise control of composition and length of nanowires using the
conventional forward approach. Herein, we report the self-assembly
inverse growth of CsPbBr3 micronanowires (MWs) (CsPb2Br5 → CsPbBr3 + PbBr2↑) by controlling phase transition from CsPb2Br5 to CsPbBr3. The two-dimensional (2D) structure
of CsPb2Br5 serves as nucleation sites to induce
initial CsPbBr3 MW growth. Also, phase transition allows
crystal rearrangement and slows down crystal growth, which facilitates
the MW growth of CsPbBr3 crystals along the 2D planes of
CsPb2Br5. A CsPbBr3 MW photodetector
constructed based on the inverse growth shows a high responsivity
of 6.44 A W–1 and detectivity of ∼1012 Jones. Large grain size, high crystallinity, and large thickness
can effectively alleviate decomposition/degradation of perovskites,
which leads to storage stability for over 60 days in humid environment
(relative humidity = 45%) and operational stability for over 3000
min under illumination (wavelength = 400 nm, light intensity = 20.06
mW cm–2).