Fast Crystallization-Deposition of Orderly Molecule Level Heterojunction Thin Films Showing Tunable Up-Conversion and Ultrahigh Photoelectric Response

Abstract

Molecular cocrystals have received much attention for tuning physicochemical properties in pharmaceutics, luminescence, organic electronics, and so on. However, the effective methods for the formation of orderly cocrystal thin films are still rather limited, which have largely restricted their photofunctional and optoelectronic applications. In this work, a fast crystallization-deposition procedure is put forward to obtain acridine (AD)-based cocrystals, which are self-assembled with three typical isophthalic acid derivatives (IPA, IPB, and TMA). The obtained donor–acceptor cocrystal complexes exhibit an adjustable energy level, wide range of photoluminescence color, and rotational angle-dependent polarized emission. The orderly and uniform cocrystal thin films further present tunable one-/two-photon up-conversion and different semiconductor properties. Particularly, AD-TMA cocrystal thin film shows a rare example of a molecule level heterojunction with the alternating arrangement of AD electronic acceptor layers and TMA electronic donor layers, and thus, provides a way for efficient mobility and separation of electron–hole pairs. A large on–off photocurrent ratio of more than 10 4 can be achieved for the AD-TMA thin film, which is higher than state-of-the-art molecular semiconductor systems. Therefore, this work extends the application scopes of orderly cocrystal thin film materials for future luminescent and optoelectronic micro-/nanodevices.

Manipulating Light‐Induced Dynamic Macro‐Movement and Static Photonic Properties within 1D Isostructural Hydrogen‐Bonded Molecular Cocrystals

“…In co‐crystals, the molecular stacking fashions and basic intermolecular interactions (e.g., hydrogen bonding, van der Waals and electrostatic forces) can be rationally tailored by selecting suitable target molecule and the co‐assembled units (co‐formers) [34–39] . Thus, the co‐crystals may emerge novel photo‐related properties that are different from the sum of individual molecules [9, 40–51] . For example, Morimoto and Ire have developed a co‐crystal of a diarylethene compound with perfluoronaphthalene in a 1:2 ratio.…”

Long-lived room temperature phosphorescence of organic–inorganic hybrid systems

“…Compared to their inorganic counterpart, organic luminescent molecules generally offer superiorities in simple processing and an easily adjustable structure, which is in favor of the fabrication of flexible and soft optoelectronic devices. 7 However, pure organic luminophores are traditionally believed to exhibit weak or inefficient room temperature phosphorescence emission because transitions between singlet and triplet states are forbidden. Even if there is an occasional transition, it will be quenched by oxygen and moisture during the longevity of triplet excitons.…”

“…It is illustrated that the intermolecular interactions, molecular orientation/ arrangement and packing modes have great influence on optical properties of bulk materials. 7 The incorporation of inorganic components can realize more molecular conformations and stacking modes of organic molecules and adjust the electronic structure to a large extent. The heavy atom effect from metal ions/clusters possesses a degree of spin-orbit coupling for the promotion of singlet-triplet conversion.…”

Manipulating Light‐Induced Dynamic Macro‐Movement and Static Photonic Properties within 1D Isostructural Hydrogen‐Bonded Molecular Cocrystals

“…[34][35][36][37][38][39] Thus,the co-crystals may emerge novel photorelated properties that are different from the sum of individual molecules. [9,[40][41][42][43][44][45][46][47][48][49][50][51] Fore xample,M orimoto and Ire have developed aco-crystal of adiarylethene compound with perfluoronaphthalene in a1 :2 ratio.T he resulting co-crystal had areversible photo-induced bending motion owing to the photo-generated ring-close reaction. [52] However,t od ate, controlling the dynamic photo-mechanical behaviors of the same molecule based on its co-crystal formation remains very challenging.T his challenge is particularly difficult for isostructural molecular crystals.…”