Designing High Performance Nonfullerene Electron Acceptors with Rylene Imides for Efficient Organic Photovoltaics

Abstract

Improving carrier mobility, redox stability, blend morphology, and photovoltaic performance while elucidating structure–property relationships remains an important design goal for nonfullerene electron acceptors (NFAs) for organic solar cells. Although numerous NFAs have been created from rylene diimide electron-deficient building blocks, they have shown far inferior photovoltaic properties compared to benchmark fused-ring electron acceptors (FREAs) such as ITIC. Herein we show that new bis­(naphthalene-imide)­arylenelidenes (BNIAs), incorporating rylene-imide end-capping groups via methine bridges in donor–acceptor architectures, are endowed with enhanced electrochemical redox stability, high carrier mobilities, and high photovoltaic performance. Pairing of those BNIAs that are also FREAs, NIDT and NIBT, respectively, with donor polymer PBDB-T produced 10.0–10.8% efficient photovoltaic devices, which are comparable to benchmark ITIC devices. Blends of FREAs NIDT and NIBT and those of non-FREA NITV were found to have similar electron mobilities, demonstrating that the much higher photovoltaic efficiency of NIDT and NIBT devices does not originate from enhanced charge transport but from differences in blend morphology and blend photophysics. The results demonstrate that incorporating rylene imides into molecular architectures through the methine-bridged donor–acceptor coupling motif is a promising design strategy toward more efficient and electrochemically rugged materials for organic solar cells.

Recent advances in high-performance organic solar cells enabled by acceptor–donor–acceptor–donor–acceptor (A–DA′D–A) type acceptors

“…Typically, A-D-A type acceptors can be reasonably designed and regulated through fused core variation, 69,76-86 side chain engineering, [87][88][89][90] and end group modification. 11,73,[91][92][93][94][95][96][97][98] As such, similar strategies can be also applied to design novel A-DA 0 D-A type acceptors, especially the big Y family. In the following text, we will elaborate on these molecular design strategies with selected examples.…”

Aminonaphthalimide‐Based Molecular Cathode Interlayers for As‐Cast Organic Solar Cells

“…[20][21][22][23] Among them, PFN-based polymers are limited in further processing considerations due to strict thin thickness (5-10 nm). [24] Derivatives of imide and amine-substituted small molecules or polymers are prime examples that have received extensive attention as cathode interlayers in OSCs due to high electron affinity and mobility, [25][26][27][28] especially for NDI-and PDIbased conjugated small molecules. [15,[29][30][31][32] However, the imidebased interlayer materials have inevitably verbose multistep synthesis and tedious purification steps.…”

Recent Advances in Non-Fullerene Acceptors of the IDIC/ITIC Families for Bulk-Heterojunction Organic Solar Cells

“…Kolhe et al [45] reported earlier this year the synthesis of a novel NFA, a3, which contains the unusual naphthaleneimide mono-ketone as the electron rich end-capping group. A3 showed an absorption maximum at a lower wavelength with respect to a2, demonstrating that the modified naphthalene imide does not possess an optimal electron withdrawing character.…”