Controllable Fabrication of In‐Series Organic Heterostructures for Optical Waveguide Application

Organic heterostructures have been demonstrated to be excellent candidates for application in photonic components such as modulators and optical switches, but the controllable fabrication of organic heterostructures remains a considerable challenge due to the lattice mismatch and weak intermolecular forces. In this study, a photochromic strategy is demonstrated to fabricate in‐series organic heterostructures with high controllability and designability by selectively covering a portion of the organic microcrystals. Radiative energy transfer is found in the blue‐green fluorescent 2‐block of the organic heterostructure, which acts as the basic component unit, leading to the unique passive/active mixed waveguide mode. Furthermore, optical waveguides with switchable output light wavelength‐bands can be constructed based on the 3‐block and 5‐block heterostructures. By changing the input ports on the heterostructures, the blue, blue/green, or green wavelength band can be selectively outcoupled, thus indicating the potential of the organic heterostructures to be utilized in future photonic systems. A controllable photochromic strategy is demonstrated to fabricate in‐series organic heterostructures. The unique passive/active mixed waveguide mode is found due to the radiative energy transfer (RET). Furthermore, optical waveguides with switchable output light wavelength‐band can be constructed based on the heterostructures, indicating the potential applications in future photonic systems.