Rational Modified Organic Functional Charge‐Transfer Complexes toward Optical/Photothermal Behavior Tuning through Decay Pathway Regulation

Abstract Doping has been proven to be a good way to regulate the optical and electrical properties of the active elements including both inorganic and organic materials. In this paper, the study demonstrates a bipolar doping strategy for an intrinsic charge‐transfer binary‐complex through the use of p‐ and n‐type dopants, which incorporate toward highly‐ordered ternary complexes. Benefitting from the good lattice matching and energy level tuning, the supramolecular system with a large doping concentration range (0 ≤ x ≤ 50% or 40%) assembles into the original crystal lattice and exhibits tunable luminescence or quenching phenomena even at very low ratio. The 7h‐benzo[c]carbazole (BCZ) dopped cocrystals show yellow–green to red emission due to the Förster resonance energy transfer (FRET); while only 5% 7,7,8,8‐tetracyanoquinodimethane (TCNQ) dopant can bring superior photothermal (PT) behavior with a high PT conversion efficiency up to 75.3%, owing to the efficient non‐radiative decay way contribution. It is believed that the strong π–π interactions and free rotation of −C(C≡N)₂ promote this decay way transition. This work on the charge‐transfer complex doping system suggests the great potential in optical, photothermal imaging, and therapy applications as well as information memory and photo sensing.