Organic lateral heterostructures with interfacial fluctuation for polarization-resolved photonics.

Organic lateral heterostructures (OLHs) based on two-dimensional (2D) molecular crystals are formed through the coplanar assembly of multiple components, and they hold great promise for optoelectronic applications. However, the precise construction of 2D OLHs with noncoplanar epitaxial layers remains challenging, limiting further exploration of lateral heterojunctions. Here, we present a stepwise vapor-phase growth strategy for synthesizing 2D OLHs with interfacial fluctuation, forming convex, flat, and concave architectures. During the lateral epitaxial growth processes, higher growth temperatures enhance molecular deposition, driving the transition of the secondary component from in-plane to out-of-plane growth. Consequently, the epitaxial layer thickness is precisely tuned from 20 to 800 nm by increasing the growth temperature. The resulting OLHs exhibit orthogonally polarized exciton conversion, with dual photoluminescence emission bands at 450 and 670 nm, functioning as multimode photonic converters. These findings provide a strategy to regulate the epitaxial growth route of 2D OLHs, paving the way for integrated photonic circuits.