Photoinduced Electron Transfer in Asymmetrical Perylene Diimide: Understanding the Photophysical Processes of Light-Absorbing Nonfullerene Acceptors

Abstract

In bulk-heterojunction-based organic photovoltaics, strong light-absorbing ability is one of the most important advantages of nonfullerene acceptors prior to fullerene derivatives. Herein, a series of electron-donating units was asymmetrically connected at the imide positions of perylene diimide (PDI), which is a classic-electron acceptor building block. The photoinduced electron-transfer behaviors were compared in different substitutions by steady/time-resolved spectroscopy and theoretical simulation. The electron-donating ability as well as the donor–acceptor distance has a significant impact on the photoinduced electron transition from electron-donating units to the PDI core. Because of the process of charge transfer at excited states, a fast nonradiative deactivation is observed for the PDIs with relatively strong electron substituent. These results would help us to understand the electron-transfer processes from donor to acceptor in the case of the excited electron-acceptor molecule.

Through-Space Conjugation: An Effective Strategy for Stabilizing Intramolecular Charge-Transfer States

“…Therefore, the lifetime of the ICT state is very short, which greatly limits the optoelectronic performance in certain areas. 7 Generally, short and wellconjugated bridges can help to increase the rate of the charge separation process and facilitate charge migration, 8,9 but the resulting stronger D−A interactions will accelerate the charge recombination process and shorten the lifetime of the ICT state. Hence, for the D−A molecules, it seems difficult to achieve fast charge transport and a long-lived ICT state at the same time.…”

9,10‐Imide‐Pyrene‐Fused Pyrazaacenes (IPPA) as N‐Type Doping Materials for High‐Performance Nonvolatile Organic Field Effect Transistor Memory Devices

“…The K nr / K r ratio increases as the electron withdrawing ability of the group increases. It can be attributed to the increased driving force to ICT state which thus leads to more significant nonradiative transition . Compounds PPA‐NO 2 and IPPA‐NO 2 show the highest K nr / K r ratio of 8.71 and 7.11, confirming strong ICT state and large dipole moment in these molecules …”

“…[23] Compounds PPA-NO 2 and IPPA-NO 2 show the highest K nr /K r ratio of 8.71 and 7.11, confirming strong ICT state and large dipole moment in these molecules. It can be seen that the K nr of all these compounds is larger than K r , which indicates the strong ICT state in these compounds.…”

“…It is known that the strong ICT state can decrease fluorescence intensity and increase the proportion of energy dissipation caused by nonradiative transition . In order to investigate the charge transfer dynamics, the time resolved emission spectra were performed (shown in Figure S6, Supporting Information), and the related parameters such as fluorescence quantum yield (FQY) are listed in Table 1 .…”

“…[23] In order to investigate the charge transfer dynamics, the time resolved emission spectra were performed (shown in Figure S6, Supporting Information), and the related parameters such as fluorescence quantum yield (FQY) are listed in Table 1. [23] In order to investigate the charge transfer dynamics, the time resolved emission spectra were performed (shown in Figure S6, Supporting Information), and the related parameters such as fluorescence quantum yield (FQY) are listed in Table 1.…”