Electrostatic Epitaxy of Orientational Perovskites for Microlasers.

Orientational growth of single-crystalline structures is pivotal in the semiconductor industry, which is achievable by epitaxy for producing thin films, heterostructures, quantum wells, and superlattices. Beyond silicon and III-V semiconductors, solution-processible semiconductors, such as metal-halide perovskites, are emerging for scalable and cost-effective manufacture of optoelectronic devices, whereas the polycrystalline nature of fabricated structures restricts their application toward integrated devices. Here, electrostatic epitaxy, a process sustained by strong electrostatic interactions between self-assembled surfactants (octanoate anions) and Pb , is developed to realize orientational growth of single-crystalline CsPbBr microwires. Strong electrostatic interactions localized at the air-liquid interface not only support preferential nucleation for single crystallinity, but also select the crystal facet with the highest Pb areal density for pure crystallographic orientation. Due to the epitaxy at the air-liquid interface, direct growth of oriented single-crystalline microwires onto different substrates without the processes of lift-off and transfer is realized. Photonic lasing emission, waveguide coupling, and on-chip propagation of coherent light are demonstrated based on these single-crystalline microwires. These findings open an avenue for on-chip integration of single-crystalline materials.