A (CH 3 ) 2 CNHCH 3 PbBr 3 /CH 3 NH 3 PbBr 3 core-shell heterostructure fabricated by an in situ a-site reaction for fast response 1D perovskite photodetectors.

Benefitting from their long carrier diffusion lengths, low trap densities and high carrier mobilities, metal halide perovskites are of great value in the field of energy and optical communications. Herein, we propose a reversible organic cation reaction for (CH 3 ) 2 CNHCH 3 PbBr 3 /CH 3 NH 3 PbBr 3 core-shell microwires (MWs), in which (CH 3 ) 2 CNHCH 3 PbBr 3 grow on bulk CH 3 NH 3 PbBr 3 in acetone and then convert back to CH 3 NH 3 PbBr 3 on the surface with the action of water. The core-shell MWs present excellent stability for more than 454 days with over 80% humidity.  Moreover, the employed core-shell heterostructure significantly increases the photoluminescence lifetime and improves the rise/recovery response. The (CH 3 ) 2 CNHCH 3 PbBr 3 /CH 3 NH 3 PbBr 3 core-shell heterostructure demonstrates excellent stability and fast response (2.8 ms/0.8 ms), which is anticipated to find comprehensive applications in future optical communication of one-dimensional devices.