In this work, an effectual strategy of constructing polar small molecule acceptors (SMAs) to promote fill factor (FF) of nonfullerene polymer solar cells (PSCs) is first reported. Three asymmetrical SMAs of IDT6CN, IDT6CN-Th, and IDT6CN-M, which own large dipole moments, are designed and synthesized. The PSCs based on three polar SMAs exhibit apparently higher FFs compared with their symmetrical analogues. The asymmetrical design strategy accompanied with side chain and end group engineering makes IDT6CN-Th- and IDT6CN-M-based nonfullerene PSCs achieve high power conversion efficiency with FFs approaching 77%.

A novel small molecule acceptor MeIC with a methylated end-capping group is developed. Compared to unmethylated counterparts (ITCPTC), MeIC exhibits a higher lowest unoccupied molecular orbital (LUMO) level value, tighter molecular packing, better crystallites quality, and stronger absorption in the range of 520-740 nm. The MeIC-based polymer solar cells (PSCs) with J71 as donor, achieve high power conversion efficiency (PCE), up to 12.54% with a short-circuit current (J ) of 18.41 mA cm , significantly higher than that of the device based on J71:ITCPTC (11.63% with a J of 17.52 mA cm ). The higher J of the PSC based on J71:MeIC can be attributed to more balanced μ /μ , higher charge dissociation and charge collection efficiency, better molecular packing, and more proper phase separation features as indicated by grazing incident X-ray diffraction and resonant soft X-ray scattering results. It is worth mentioning that the as-cast PSCs based on MeIC also yield a high PCE of 11.26%, which is among the highest value for the as-cast nonfullerene PSCs so far. Such a small modification that leads to so significant an improvement of the photovoltaic performance is a quite exciting finding, shining a light on the molecular design of the nonfullerene acceptors.

Developing excited-state intramolecular proton transfer (ESIPT) emitters with high photoluminescence quantum yields (Φs) and long fluorescence lifetimes in solid state remains a formidable challenge. In this study, we integrated the molecular design tactics of thermally activated delayed fluorescence (TADF) into ESIPT molecules with the goals of improving their Φs and increasing their fluorescence lifetimes. Two proof-of-concept molecules, PXZPDO and DMACPDO, were developed by adopting symmetric D-π-A-π-D molecular architectures (where D and A represent donors and acceptors, respectively) featuring electron-donating phenoxazine or a 9,9-dimethyl-9,10-dihydroacridine moiety, an ESIPT core β-diketone, and phenylene π-bridges. Both molecules exhibited sole enol-type forms stabilized by intramolecular hydrogen bonds and exhibited a unique and dynamic ESIPT character that was verified by transient absorption analyses. Endowed with distinct TADF features, PXZPDO and DMACPDO showed high Φs of 68% and 86% in the film state, coupled with notable delayed fluorescence lifetimes of 1.33 and 1.94 μs, respectively. Employing these ESIPT emitters successfully achieved maximum external quantum efficiencies (ηs) of 18.8% and 23.9% for yellow and green organic light-emitting diodes (OLEDs), respectively, which represent the state-of-the-art device performances for ESIPT emitters. This study not only opens a new avenue for designing efficient ESIPT emitters with high Φs and long fluorescence lifetimes in solid state but also unlocks the huge potential of ESIPT emitters in realizing high-efficiency OLEDs.

In this article, we designed and synthesized a novel small molecule acceptor of ITCPTC with thiophene‐fused ending group by employing a new active methylene precursor of CPTCN. The ITCPTC‐based polymer solar cells with PBT1‐EH as a donor achieved very high power conversion efficiencies (PCEs) of up to 11.8% with a remarkably enhanced fill factor (FF) of 0.751, a near 20% boost in PCE with respect to the ITIC‐based control device. These values are among the highest PCEs and FFs for polymer solar cells (PSCs). In the whole study, we made contrasts with ITIC to understand the reasons of excellent performance of ITCPTC‐based PSCs through various measurements, such as GIXD and RSoXS. We revealed that the simple modification of ITIC into ITCPTC not only change the material electronic structure, but also mediates the material interactions and crystallization, which contribute together to the excellent performance of ITCPTC‐based PSCs.

Thermally activated delayed fluorescence (TADF) polymers are designed and synthesized by grafting the TADF emitter to the side chain of the polycarbazole backbone. By employing these TADF polymers with large ratio of delayed fluorescence component and high photoluminescence quantum yield as the emitters, the solution-processed light-emitting diodes achieve a maximal external quantum efficiency of 16.1% at a luminance of around 100 cd m .

Protein tyrosine kinase 7 (PTK7) and cancer-associated fibroblasts (CAFs) play important roles in cancer stemness, respectively. However, little is known about interaction between CAFs and PTK7 in cancers. In this study, we showed that PTK7 was significantly correlated with the Wnt/β-Catenin pathway and aggressive clinicopathologic features in human head and neck squamous cell carcinoma (HNSCC). Meanwhile, animal experiments showed that PTK7 enhanced chemoresistance and lung metastasis of HNSCC in vivo. In addition, co-immunoprecipitation (co-IP) assay demonstrated that POSTN secreted by CAFs was a potential upstream ligand of PTK7 which might act as a receptor. Further analysis revealed that POSTN promoted the cancer stem cell (CSC)-like phenotype via PTK7–Wnt/β-Catenin signaling, including the proliferation and invasion of HNSCC cells in vitro, as well as tumor initiation and progression in vivo. Collectively, our study proved that CAF-derived POSTN might promote cancer stemness via interacting with PTK7 in HNSCC, suggesting that the combination of POSTN and PTK7 might be a potential prognostic and diagnostic indicator and a  promising therapeutic target.

Carbazole-dendronized TADF emitters enable non-doped, solution-processed OLEDs to achieve a high EQE of 13.8% and a low efficiency roll-off simultaneously.

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