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All-polymer solar cells (all-PSCs) have received tremendous focus recently owing to their superior mechanical robustness and excellent thermal stability. However, only few studies on the application of small-molecule acceptors (SMAs) in all-PSCs have been reported. Herein, a highly crystalline non-fused ring (NFR) SMA, namely DFTQA-2FIC, was introduced as a third component to enhance the performance of an all-PSC based on PBDB-T:N2200. After introducing DFTQA-2FIC into the PBDB-T:N2200 blend, the energy levels of DFTQA-2FIC did not only cascade with those of PBDB-T and N2200, but also formed a more uniform and continuous interpenetrating structure and caused better phase separation, thereby mitigating losses caused by electron–hole recombination, minimizing energy dissipation, and significantly elevating charge transport with a well-balanced performance. Encouragingly, an impressively improved power conversion efficiency (PCE) from 6.45% in binary all-PSCs to 8.07% in the ternary system, with an increase of 25.1%, was obtained, which is one of the highest reported for PBDB-T:N2200-based all-PSCs thus far. This study highlights the potential of this type of NFR-SMA as a third component for highly efficient ternary OSCs. [ABSTRACT FROM AUTHOR]

In organic solar cells (OSCs), the intricate synthesis and lower yield of ladder-type fused ring small molecule receptors (FR-SMAs) have prompted the quest for simpler, higher yielding non-fused ring (NFR)-SMAs. In this paper, a type of NFR asymmetrical SMA with an A–D–π–A structure, namely DPCT8-4F and DPCT10-4F, was primarily designed and synthesized, in which an alkyl chain dipyran (DP) ring, cycllopentadithiophene (CT) and fluorinated 1,1-dicyanomethylene-3-indanone (4F) are employed as the donor (D) unit, π-bridge and acceptor (A) terminals, respectively. The influence of the alkyl chain originating from the DP unit on their optical, electrochemical and photovoltaic properties was systematically investigated. The DPCT8-4F with n-octane chains exhibited enhanced crystallinity and molecular packing compared to the DPCT10-4F with n-decane chains. After being blended with the polymer donor PBDB-T, the OSCs based on PBDB-T:DPCT8-4F demonstrate an impressive power conversion efficiency (PCE) of 12.52%, surpassing that of 11.68% for the DPCT10-4F-based ones. This work demonstrates that these asymmetric NFR-SMAs can improve the efficiency of OSCs by pairing alkyl chains on the dipyran ring. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) organic light‐emitting diodes (OLEDs) suffer from the low external electroluminescence (EL) quantum efficiency (EQE), which is a critical obstacle for potential applications. Herein, 1‐oxo‐1‐phenalene‐2,3‐dicarbonitrile (OPDC) is employed as an electron‐withdrawing aromatic ring, and by incorporating with triphenylamine (TPA) and biphenylphenylamine (BBPA) donors, two novel NIR emitters with thermally activated delayed fluorescence (TADF) characteristics, namely OPDC‐DTPA and OPDC‐DBBPA, are first developed and compared in parallel. Intense NIR emission peaks at 962 and 1003 nm are observed in their pure films, respectively. Contributed by the local excited (LE) characteristics in the triplet (T1) state in synergy with the charge transfer (CT) characteristics for the singlet (S1) state to activate TADF emission, the solution processable doped NIR OLEDs based on OPDC‐DTPA and OPDC‐DBBPA yield EL peaks at 834 and 906 nm, accompanied with maximum EQEs of 0.457 and 0.103 %, respectively, representing the state‐of‐the‐art EL performances in the TADF emitter‐based NIR‐OLEDs in the similar EL emission regions so far. This work manifests a simple and effective strategy for the development of NIR TADF emitters with long wavelength and efficiency synchronously. [ABSTRACT FROM AUTHOR]