Unprecedented Improvement of Near-Infrared Photothermal Conversion Efficiency to 87.2% by Ultrafast Non-radiative Decay of Excited States of Self-Assembly Cocrystal

Abstract

Near-infrared (NIR) photothermal conversion is of great interest in many fields. Here, a self-assembly organic cocrystal (N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) and pyromellitic dianhydride (PMDA)) with strong absorption in NIR range is constructed, with widespread absorption (200–1500 nm) and very high NIR photothermal conversion efficiency (87.2%). Essentially, in this cocrystal, a small HOMO–LUMO gap of donor–acceptor pair boosts the absorption ability of this cocrystal in the NIR range. The mixed stacking structure significantly enhances the intermolecular interactions as well as the electron–hole delocalization, suppressing the emission processes, leading to nonradiative decay processes from excited states. Strong intermolecular interactions enable the cocrystal to have dense electronic energy levels, leading to a high proportion (94.4%) vibrational cooling and internal conversion processes with ultrafast excited-state relaxation (0.12 ps), which contributes to high NIR photothermal conversion efficiency. Furthermore, the cocrystal has exhibited capable ability for being an excellent candidate for a NIR photothermal therapy agent.

Thin films of electron donor–acceptor complexes: characterisation of mixed-crystalline phases and implications for electrical doping

“…9,20,21 The low gap offers the possibility to use EDA complexes as infra-red absorber for photovoltaics, photo-detectors and photo-thermal converters. [22][23][24] EDA complex formation was found also in photovoltaic systems, 25 where interaction between donor and acceptor is present only at the grain boundaries of separated D and A phases. The weakly absorbing EDA complex of zinc-phthalocyanine and fullerene C60 was used in infra-red detectors with optical cavities to increase the absorption of the complex.…”

An n -Type All-Fused-Ring Molecule with Narrow Bandgap

“…[13][14][15] Narrow bandgap organic compounds possess strong absorption and/or emission in near-infrared (NIR) region and are required for solar-energy-related applications, bio-imaging and medical applications. [16][17][18][19][20] Generally, organic molecules with narrow bandgaps can be designed by introducing of electron donating-accepting (D-A) structures and quinoid structures. 21,22 N-Type organic semiconductors are essential materials in OFETs and OSCs.…”

Enhanced luminescence of single-benzene fluorescent molecules through halogen bond cocrystals

“…20 Li et al discovered a selfassembled organic cocrystal of N,N,N′,N′-tetramethyl-pphenylenediamine (TMPD) and pyromellitic dianhydride (PMDA), with high near-infrared photothermal conversion efficiency. 21 As small π-conjugated systems, single benzene luminescent molecules have attracted considerable research attention in the past few years due to their excellent properties and easy preparation. For instance, Zhang et al found two polymorphs of 2,5-bisIJ(thiophen-2-ylmethyl)amino)dimethyl terephthalate crystals exhibiting a flexible optical waveguide.…”