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

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 Forster 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 pi-pi interactions and free rotation of -C(C equivalent to 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. A bipolar doping strategy is reported for the charge-transfer complex photo-responsive behavior modification. The mixed supramolecular system with a certain donor doping concentration range exhibits tunable fluorescence emission, due to the Forster resonance energy transfer; for electron-acceptor dopping, only 5% dopant can introduce excellent photothermal conversion ability, because of the efficient non-radiative transition. image