A Soluble Ladder‐Conjugated Star‐Shaped Oligomer Composed of Four Perylene Diimide Branches and a Fluorene Core: Synthesis and Properties

Abstract

A new ladder‐conjugated star‐shaped oligomer electron‐transporting material TetraPDI‐PF, with four perylene diimide (PDI) branches and a fluorene core, was efficiently synthesized. The oligomer is highly soluble in dichlorobenzene with a solubility of 155 mg mL−1, which is higher than those of PDI (35 mg mL−1) and PDI‐Phen (70 mg mL−1). Demonstrated by thermogravimetric analysis (TGA), the oligomer exhibits excellent thermal stability with the decomposition temperature (Td) of 291.2 °C, which is 65 °C higher than that of PDI. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to investigate the electrochemical properties. Although the CV curves of TetraPDI‐PF are successively scanned for 15 cycles, they still remain invariable reduction potentials. The oligomer also shows outstanding photostability, even better than PDI, which maintains 99 % fluorescence intensity after irradiation for 10 min using maximum laser intensity. In the steady‐state space‐charge‐limited current (SCLC) devices, TetraPDI‐PF exhibits higher intrinsic electron mobility of 2.22×10−5 cm2 V−1 s−1, three orders of magnitude over that of PDI (3.52×10−8 cm2 V−1 s−1). The bulk heterojunction (BHJ) organic solar cells (OSCs) using TetraPDI‐PF as non‐fullerene acceptors and P3HT as donors give optimum power conversion efficiency (PCE) of 0.64 %, which is 64 times that of the PDI:P3HT BHJ cells.

Fine‐Tuning the 3D Structure of Nonfullerene Electron Acceptors Toward High‐Performance Polymer Solar Cells

“…. Many known nonfullerene electron acceptors, such as naphthalene diimide (NDI), perylene diimide (PDI), tetraazabenzodifluoranthene diimide (BFI), and bis(naphthalene imide)diphenylanthrazoline (BNIDPA) derivatives, have a rigid 2D π‐conjugated structure whereas others combine two or more electron‐deficient chromophores to form a π‐conjugated framework with a nonplanar 3D conformation owing to different orientation of chemical bonding and/or steric effects. In both cases, the molecular conformation in 3D space is a critical factor that affects many molecular and bulk properties of the nonfullerene acceptors: (i) the electron delocalization and thus the electronic structures (e.g., a twisted/nonplanar structure can reduce electron delocalization whereas a coplanar structure can favor increased electron delocalization); (ii) intermolecular interactions (π–π stacking, hydrogen bonding, dipole–dipole interaction, etc.…”

Perinone—New Life of an Old Molecule

“…Moreover, charge carrier mobilities show drastically different directional anisotropy and atomic force microscopic analyses revealed a strong correlation between the film morphology and the charge transport behavior. The molecules are arranged into ordered hexagonal packing with edge-on orientation in thin films [48,50]. The charge transport in discotic systems is highly influenced by the local arrangement of stacked π-conjugated cores and the length, type (linear/branched), and chemical structure of the side chains [51,52].…”

A phenothiazine-fused electroactive bilayer helicene: design, synthesis, ACQ-to-AIE transformation and photophysical properties

“…17 J. Xia et al synthesized a star-shaped PDI-based helical unit as an electron acceptor. 5 Perylene derivatives are some of the most studied luminogens, because of their good electron-transporting nature, supramolecular structure, good solubility 18 and different applications. However, such molecules are heavily affected by aggregationcaused quenching (ACQ), which affects their potential properties.…”