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The emergence of Y6 and its derivatives has significantly advanced organic photovoltaics (OPVs). However, the limited design strategies for Y6-based non-fullerene acceptors (NFAs) in absorbing visible light restrict their application in indoor OPVs (IOPVs). Furthermore, the reliance on additive-assisted chlorinated solvents for processing photoactive layers poses a significant barrier to IOPV commercialization. Herein, we synthesized two IPC-ended NFAs (IPC-BBO-IC2F and IPC-BBO-IC2Cl) and two IPC1CF3-ended NFAs (IPC1CF3-BBO-IC2F and IPC1CF3-BBO-IC2Cl). These asymmetric NFAs, featuring two distinct groups at the molecular ends, demonstrated blue-shifted absorption and elevated energy levels compared to Y6, offering a promising approach to harness indoor light and achieve higher open-circuit voltages more effectively. IOPVs processed without additives and using o-xylene, based on PM6:IPC1CF3-BBO-IC2F and PM6:IPC1CF3-BBO-IC2Cl, showed high efficiencies of 26.5% and 24.2%, respectively, under 1000-lux light-emitting diode (LED) illumination. These efficiencies surpass those of IOPVs that employ IPC-ended NFAs or Y6. Moreover, ternary IOPVs based on PM6:Y6:IPC1CF3-BBO-IC2F and PM6:Y6:IPC1CF3-BBO-IC2Cl achieved notable efficiencies of 26.9% and 27.1% under 1000 lux-LED illumination and 30.2% and 29.2% under 1000 lux-fluorescent light (FL) illumination, respectively. These findings underscore the potential of the IPC1CF3 end group in the asymmetric structural modification of Y6 to enhance the performance of IOPVs using additive-free and environmentally benign solvents. [ABSTRACT FROM AUTHOR]

It remains challenging to fabricate efficient, scalable large-area organic solar cells (OSCs) owing to the unfavorable morphology of photoactive blend films. To address this challenge, two asymmetric nonfullerene acceptors (NFAs) IPC1CN-BBO-IC2F and IPC1CN-BBO-IC2Cl are synthesized, where 12,13-bis(2-butyloctyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4- e]thieno[2'",3'":4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno-[3,2- b]indole (BBO) is the molecular core, and two types of end groups are appended to its ends, namely the 9H-indeno[1,2-fe]pyrazine-2,3,8-tricarbonitrile (IPC1CN) end group and one of 2-(5,6-dihalo-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile end groups (IC2F or IC2Cl). These NFAs facilitate effective tuning of light absorption and energy levels, offer high carrier mobilities, and allow for the formation of appropriate morphologies. Note that these benefits apply even to large-area devices, unlike typical Y6-based NFAs. In addition, a random copolymer PM6-PBDBT(55) is synthesized and its energy levels are optimally matched with those of the asymmetric NFAs. The blade-coated 1 cm2-area OSCs based on PM6-PBDBT(55):IPC1CN-BBO-IC2Cl exhibit a PCE of 14.12%, which is higher than that of PM6-PBDBT(55)-IPC1CN-BBO-IC2F-based OSCs. More importantly, the PM6-PBDBT(55):IPC1CN-BBO-IC2Cl-based large-area (58.50 cm2) modules yield an impressive PCE of 11.28% with a small cell-to-module loss in fill factor. These results suggest that a combination of the asymmetric molecular design using the IPC1CN group and the terpolymer strategy will pave a new path for fabricating highly efficient and scalable large-area OSCs. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) demonstrating high power conversion efficiencies have been mostly fabricated using halogenated solvents, which are highly toxic and harmful to humans and the environment. Recently, non-halogenated solvents have emerged as a potential alternative. However, there has been limited success in attaining an optimal morphology when non-halogenated solvents (typically o-xylene (XY)) were used. To address this issue, we studied the dependence of the photovoltaic properties of all-polymer solar cells (APSCs) on various high-boiling-point non-halogenated additives. We synthesized PTB7-Th and PNDI2HD-T polymers that are soluble in XY and fabricated PTB7-Th:PNDI2HD-T-based APSCs using XY with five additives: 1,2,4-trimethylbenzene (TMB), indane (IN), tetralin (TN), diphenyl ether (DPE), and dibenzyl ether (DBE). The photovoltaic performance was determined in the following order: XY + IN < XY + TMB < XY + DBE ≤ XY only < XY + DPE < XY + TN. Interestingly, all APSCs processed with an XY solvent system had better photovoltaic properties than APSCs processed with chloroform solution containing 1,8-diiodooctane (CF + DIO). The key reasons for these differences were unraveled using transient photovoltage and two-dimensional grazing incidence X-ray diffraction experiments. The charge lifetimes of APSCs based on XY + TN and XY + DPE were the longest, and their long lifetime was strongly associated with the polymer blend film morphology; the polymer domain sizes were in the nanoscale range, and the blend film surfaces were smoother, as the PTB7-Th polymer domains assumed an untangled, evenly distributed, and internetworked morphology. Our results demonstrate that the use of an additive with an optimal boiling point facilitates the development of polymer blends with a favorable morphology and can contribute to the widespread use of eco-friendly APSCs. [ABSTRACT FROM AUTHOR]

Despite the outstanding photovoltaic performance of symmetrical Y6, its use is limited in that only chloroform (CF), a highly volatile processing solvent, can induce favorable morphology. This dependence on a particular solvent poses an obstacle to mass production. Here, we investigate the effect of symmetry‐breaking of nonfullerene acceptors (NFAs) on device performance and processability by employing chlorobenzene (CB) or CF processing solvents. In organic solar cells (OSCs) based on a symmetrical Y6 acceptor, a significant difference in the power conversion efficiency occurs between the OSCs fabricated using CB and those fabricated using CF. However, in OSCs based on IPC‐BEH‐IC2F with asymmetrical structure, no difference in photovoltaic performance occurs between the two OSCs. Grazing‐incidence wide‐angle X‐ray scattering measurements indicate that IPC‐BEH‐IC2F exhibits nearly identical diffraction features in both the CB‐ and CF‐processed photoactive films, whereas Y6 shows markedly different stacking structures. Because of these morphological features, OSCs based on Y6 are associated with a relatively large energy loss difference in CB and CF, whereas OSCs based on IPC‐BEH‐IC2F show no significant difference in energy loss. The introduction of an asymmetrical structure can therefore be an important strategy to enhance the versatile processability of OSCs based on NFAs for future mass production. [ABSTRACT FROM AUTHOR]

Since the coronavirus pandemic, mRNA vaccines have revolutionized the field of vaccinology. Lipid nanoparticles (LNPs) are proposed to enhance mRNA delivery efficiency; however, their design is suboptimal. Here, a rational method for designing LNPs is explored, focusing on the ionizable lipid composition and structural optimization using machine learning (ML) techniques. A total of 213 LNPs are analyzed using random forest regression models trained with 314 features to predict the mRNA expression efficiency. The models, which predict mRNA expression levels post-administration of intradermal injection in mice, identify phenol as the dominant substructure affecting mRNA encapsulation and expression. The specific phospholipids used as components of the LNPs, as well as the N/P ratio and mass ratio, are found to affect the efficacy of mRNA delivery. Structural analysis highlights the impact of the carbon chain length on the encapsulation efficiency and LNP stability. This integrated approach offers a framework for designing advanced LNPs and has the potential to unlock the full potential of mRNA therapeutics., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Organic optoelectronic devices that can be fabricated at low cost have attracted considerable attention because they can absorb light over a wide frequency range and have high conversion efficiency, as well as being lightweight and flexible. Moreover, their performance can be significantly affected by the choice of the charge-selective interlayer material. Nonstoichiometric nickel oxide (NiO x ) is an excellent material for the hole-transporting layer (HTL) of organic optoelectronic devices because of the good alignment of its valence band position with the highest occupied molecular orbital level of many p-type polymers. Herein, we report a simple low-temperature process for the synthesis of NiO x nanoparticles (NPs) that can be well dispersed in solution for long-term storage and easily used to form thin NiO x NP layers. NiO x NP-based organic photodiode (OPD) devices demonstrated high specific detectivity ( D *) values of 10 12 -10 13 jones under various light intensities and negative biases. The D * value of the NiO x NP-based OPD device was 4 times higher than that of a conventional poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based device, an enhancement that originated mainly from the 16 times decreased leakage current. The NiO x NP-based OPD device demonstrated better reliability over a wide range of light intensities and operational biases in comparison to a device with a conventional sol-gel-processed NiO x film. More importantly, the NiO x NP-based OPD showed long-term device stability superior to those of the PEDOT:PSS and sol-gel-processed NiO x -based devices. We highlight that our low-temperature solution-processable NiO x NP-based HTL could become a crucial component in the fabrication of stable high-performance OPDs.