In this work, three small molecular donors (SMDs) S35, S35–1Si, and S35–2Si, with 3,5-difluorophenyl-substituted benzodithiophene as the central 2-dimensional unit to combine different numbers of siloxane-terminated side chain, were synthesized for all-small-molecule organic solar cells (ASM-OSCs). The three SMDs showed comparable film absorption peaks at 570 nm and optical band gaps of 1.8 eV. Relative to S35 and S35–1Si with symmetric alkyl side chains and asymmetric side chains on the central unit, respectively, the S35–2Si carrying two symmetric siloxane-terminated side chains displayed largely elevated melting and crystalline temperatures, lowered surface energy, and modulated molecular orientation. The three SMDs possessed edge-on dominated molecular orientations of their neat films; however, a big difference was found for their blend films with nonfullerene acceptor Y6. The S35:Y6 and S35–1Si:Y6 blends exhibited edge-on and face-on bimodal orientations but the S35–2Si:Y6 blend showed pure face-on orientation, indicating quite different donor:acceptor intermolecular interactions. Some large domains existed in the S35:Y6 and S35–1Si:Y6 blends, but could be suppressed by the S35–2Si:Y6 blend, leading to a more balanced charge transport. In ASM-OSCs, the two S35:Y6 and S35–1Si:Y6 active layers showed comparable power conversion efficiencies (PCE) of ∼12% but a much higher efficiency of 13.50% could be achieved with the S35–2Si:Y6 active layer. Our results suggest that the siloxane-terminated side chain is promising to regulate crystalline ability of a SMD, paving a way for high performance ASM-OSCs.
Near‐infrared organic photodetector of high sensitivity is essential for various remote sensing applications. In this work, a new simple fused‐ring acceptor “NTQ” with a narrow optical bandgap of 1.11 eV is designed and synthesized to demonstrate the first near‐infrared organic photodetector example featuring a non‐fused A‐D‐A′‐D‐A molecular framework. The optimized geometry of NTQ exhibits high planarity and the relevant pristine film shows high electron mobility of 1.51 × 10−4 cm2 V−1 s−1. Moreover, the PTB7‐Th:NTQ blend can achieve relatively high and balanced hole/electron mobility even though the photo‐active layer thickness is up to 320 nm. The NTQ‐based devices exhibit high shot‐noise‐limited specific detectivity (Dsh*) of 3.72 × 1012 Jones at 1000 nm under the bias of –0.1 V and a board Dsh* response over 1012 Jones from 320 to 1070 nm. Furthermore, the device exhibits fast averaged rise and fall times of 2.02 and 2.42 µs, respectively. This work demonstrates that molecular engineering with the A‐D‐A′‐D‐A framework can endow near‐infrared photo‐active materials with high‐performing photodetectors for wide applications.
Molecular orientation in polymer solar cells (PSCs) is a critical subject of investigation that promotes the quality of bulk heterojunction morphology and power conversion efficiency (PCE). Herein, the intrinsic polymer orientation transition can be found upon delicate control over the branching point position of the irregular alkoxy side chain in difluoroquinoxaline−thiophene-based conjugated polymers. Three polymers with branching points at the third, fourth, and fifth positions away from the backbone were synthesized and abbreviated as PHT3, PHT4, and PHT5, respectively. Temperature-dependent absorption behavior manifests the polymer aggregation ability in the order of PHT3 < PHT4 < PHT5. Surprisingly, the polymer orientation transition from typical face-on to edgeon emerged between PHT4 and PHT5, as evidenced by X-ray-scattering analysis. The enhanced face-on crystallinity of PHT4 endowed the o-xyleneprocessed PHT4:IT-4Cl-based devices with the highest PCE of 13.40%. For PHT5 with stronger aggregation, the related o-xylene-processed PSCs still showed a good PCE of 12.66%. Our results demonstrate that a delicate polymer orientation transition could be realized through a precisely controlled strategy of the side chain, yielding green-solvent-processed high-performance PSCs.
Laser Tweezers Raman Spectroscopy (LTRS) is a combination of laser tweezers and Raman spectroscopy. It is a physical tool based on the mechanical effects of the laser, which can be used to study single living cells in suspension in a fast and non‐destructive way. Our work aims to establish a methodology system based on LTRS to rapidly and non‐destructively detect the resistance of acute lymphoblastic leukemia (ALL) cells and to provide a new idea for the evaluation of the resistance of ALL cells. Two specific adriamycin‐resistant and parental ALL cells BALL‐1 and Nalm6 were included in this study. Adriamycin resistant cells can induce the spectral differences, which can be detected by LTRS initially. To ensure the accuracy of the results, we use the principal components analysis (PCA) as well as the classification and regression trees (CRT) algorithms, which show that the specificity and sensitivity of LTRS are above 90%. In addition, to further clarify the chemoresistance status of ALL cells, we used the CRT models and receiver operating characteristic (ROC) curves which are based on the band data to look for some important bands and band intensity ratios that have strong pointing significance. Our work proves that LTRS analysis combined with multivariate statistical analyses have great potential to be a novel analytical strategy at the single‐cell level for rapidly evaluating the chemoresistance status of ALL cells.
Light harvesting, molecular aggregation, and orientation of photoactive materials are crucial for non-fullerene polymer solar cells. Random copolymerization is a feasible and effective way to modify the molecular structure of polymer donors. However, it is very challenging to transfer the edge-on orientation of oligothiophene-based polymers to face-on orientation. Herein, we employed random copolymerization strategy by incorporating a specific ratio of a benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (BDD)-based monomer into the backbone of a temperature-dependent polymer PFBT4T to improve the device performance. The resulting terpolymer donor PFBT4T-T20 with a comparable synthetic complexity possesses a dominant face-on orientation and weakened aggregations in solution and film, which are different from the parent polymer PFBT4T. When blended with acceptor Y14, the PFBT4T-T20-based device exhibits a more balanced carrier transport and optimal morphology and then achieved a higher efficiency of 15.60%. Our results reveal that the terpolymer strategy involving an extra component of the C2v symmetric structure can revive the oligothiophene-based conjugated polymer toward efficient non-fullerene solar cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.