Structure-Dependent Electron Affinities of Perylene Diimide-Based Acceptors

Abstract

Perylene dyes are a representative framework of electron transport (n-type) organic semiconductors. The energy of their electron transport level is the electron affinity (EA), which is an important parameter in selecting the electron transport materials for device application and of the material's electron-accepting ability. Recent studies show that EA may vary by as much as 1 eV depending on the molecular orientation owing to the electrostatic potential generated by the quadrupole moments. Because perylene dyes have a large quadrupole moment, it is essential to discuss EA combined with the molecular orientation in the sample film. In this work, we determine the EAs of perylene diimide derivatives in the solid phase using low-energy inverse photoelectron spectroscopy (LEIPS), which was developed by one of the authors. By changing the substrate and the alkyl-chain length, we systematically investigate the relationship between EA and molecular arrangement in the film to derive the general trend of the EA of perylene dyes. The results show that most of the perylene dyes' EAs are in the range from 3.7 to 4.0 eV.

Understanding Photocapacitive and Photofaradaic Processes in Organic Semiconductor Photoelectrodes for Optobioelectronics

“…From our measurements we obtain a free energy of Δ G 0 = −0.24 eV. Combining this value with the electron affinity of PTCDI, E A , PTCDI = 4.1 [ 35 ] and the PTCDI/PBS surface dipole in darkness estimated to be qV d = 0.23 eV from KPFM measurements (see Section S6, Supporting Information), we obtain the energy level of the acceptor state, E 0 OxRed = E A , PTCDI + ΔG 0 − qV d = 4.11 eV. This value compares well to the standard potential of the rate limiting, one‐electron oxygen reduction process leading to the superoxide radical anion ‐ = 4.1 eV [ 36 ] and is significantly above the level for the two‐electron process reported for the final reaction product hydrogen peroxide = 4.8 eV.…”

Excited-State Dynamics of Perylene-Based Chromophore Assemblies on Nanoporous Anodic Aluminum Oxide Membranes

“…71 SB-CS in nonpolar solution is thought to occur in part due to the appreciable quadrupole moment of solvents like toluene, 26,43 while SB-CS in aggregated rylene diimides may be due to the quadrupolar nature of their large conjugated π systems. 27,72 The quadrupole moment of the solvent, 73 or self-solvating rylene diimide in the aggregate, 72,74 may help to stabilize the CT state, making this state thermodynamically more accessible.…”

“…The tendency of closely packed chromophores to undergo SB-CS or form excimers even in the absence of solvent may be indicative of the tendency of these chromophores to self-solvate as a consequence of their interacting quadrupole moments. 72,74 In this study, we have shown that AAO membranes can be used as a scaffold to study how excited-state dynamics change as a function of average interchromophore distance and solvation with the latter being independent of how soluble the chromophore assemblies are in a particular solvent.…”

Control of supramolecular organizations by coordination bonding in tetrapyridylporphyrin thin films

“…12 On the other hand, some planar compounds with hydrogenbonding yielding groups such as 1,4,5,8-naphthalenetetracarboxylic and 3,4,9,10-perylenetetracarboxylic diimides are known to take the face-on orientation. [13][14][15][16] In these films, the hydrogen bonding forms a two-dimensional (2D) supramolecular structure along the substrate, in which the planar molecules are aligned parallel to the 2D aggregate. Yokoyama and co-workers demonstrated that several amorphous materials containing pyridine rings exhibited face-on orientation due to intermolecular hydrogen bonding.…”