For optimizing steady-state performance in organic electrochemical transistors (OECTs), both molecular design and structural alignment approaches must work in tandem to minimize energetic and microstructural disorders in polymeric mixed ionic-electronic conductor films. Herein, a series of poly(diketopyrrolopyrrole)s bearing various lengths of aliphatic-glycol hybrid side chains (PDPP-mEG; m = 2-5) is developed to achieve high-performance p-type OECTs. PDPP-4EG polymer with the optimized length of side chains exhibits excellent crystallinity owing to enhanced lamellar and backbone interactions. Furthermore, the improved structural ordering in PDPP-4EG films significantly decreases trap state density and energetic disorder. Consequently, PDPP-4EG-based OECT devices produce a mobility-volumetric capacitance product ([µC*]) of 702 F V^-1 cm^-1 s^-1 and a hole mobility of 6.49 ± 0.60 cm² V^-1 s^-1 . Finally, for achieving the optimal structural ordering along the OECT channel direction, a floating film transfer method is employed to reinforce the unidirectional orientation of polymer chains, leading to a substantially increased figure-of-merit [µC*] to over 800 F V^-1 cm^-1 s^-1 . The research demonstrates the importance of side chain engineering of polymeric mixed ionic-electronic conductors in conjunction with their anisotropic microstructural optimization to maximize OECT characteristics.

Organic Solar Cells In article number 2204871, Dong-Yu Kim and co-workers propose water treatment by inducing vortex agitation in the stirring process of the active solution for organic solar cells, which can yield good dispersion of donors and acceptors. The introduced water content for the water treatment is universally optimized in small (0.1 cm2) and large (10 cm2) organic solar cells with improved final device efficiency and stability.

For optimizing steady-state performance in organic electrochemical transistors (OECTs), both molecular design and structural alignment approaches must work in tandem to minimize energetic and microstructural disorders in polymeric mixed ionic-electronic conductor films. Herein, a series of poly(diketopyrrolopyrrole)s bearing various lengths of aliphatic-glycol hybrid side chains (PDPP-mEG; m = 2-5) is developed to achieve high-performance p-type OECTs. PDPP-4EG polymer with the optimized length of side chains exhibits excellent crystallinity owing to enhanced lamellar and backbone interactions. Furthermore, the improved structural ordering in PDPP-4EG films significantly decreases trap state density and energetic disorder. Consequently, PDPP-4EG-based OECT devices produce a mobility-volumetric capacitance product ([µC*]) of 702 F V^-1 cm^-1 s^-1 and a hole mobility of 6.49 ± 0.60 cm² V^-1 s^-1 . Finally, for achieving the optimal structural ordering along the OECT channel direction, a floating film transfer method is employed to reinforce the unidirectional orientation of polymer chains, leading to a substantially increased figure-of-merit [µC*] to over 800 F V^-1 cm^-1 s^-1 . The research demonstrates the importance of side chain engineering of polymeric mixed ionic-electronic conductors in conjunction with their anisotropic microstructural optimization to maximize OECT characteristics.

Organic Solar Cells In article number 2204871, Dong-Yu Kim and co-workers propose water treatment by inducing vortex agitation in the stirring process of the active solution for organic solar cells, which can yield good dispersion of donors and acceptors. The introduced water content for the water treatment is universally optimized in small (0.1 cm2) and large (10 cm2) organic solar cells with improved final device efficiency and stability.

Abstract Recent advances in the development of organic solar cells (OSCs) have produced power conversion efficiency (PCE) of over 19%. Various studies have been conducted on scalable coating methods that are compatible with large‐area production of organic photovoltaic modules. However, it is still difficult to control the bulk heterojunction (BHJ) morphology of the active layer during large‐scale fabrication of OSCs. This study reports a morphology‐controllable strategy in OSCs using water treatment (WT) in the stirring process of the active solution, thus resulting in vortex agitation. The effects of WT and water injection volume are investigated based on three reference cells for the optimization of small‐ and large‐area devices, and the physicochemical and optical properties of the films are compared with those without WT. The thin films with WT exhibit a smoother morphology than those without WT, indicating well‐dispersed donor–acceptor phases. Therefore, enhanced efficiencies of the films are achieved via WT. Furthermore, large‐area solar cell modules with a total effective area of 10 cm 2 are fabricated, and they exhibit superior PCEs as high as 11.92% (H‐NF‐DIW10), indicating that the WT method is a simple and effective strategy to fabricate large‐area organic photovoltaic modules.

Magnetic properties of organic materials have rarely been investigated because of the lack of compatible materials despite its remarkable potential for various applications such as spintronics. Particularly, the relationship between molecular structure and magnetic properties, including magnetization and spin orientation in organic materials, remains unexplored. In this study, a magnetically active open-shell conjugated polymer consisting solely of an open-shell diradical monomer is developed. The bulk polymer shows a typical paramagnetic behavior; however, intriguingly, the polymer films exhibit a ferromagnetic hysteresis loop. Moreover, as the polymer chains are ordered by thermal annealing, a further increase in both saturation magnetization and coercivity is observed. The thermally annealed polymer film exhibits ferromagnetic-like spin ordering at both 10 K and room temperature, as well as high air stability. Furthermore, the magnetic anisotropy depends on the direction of chain alignment and/or backbone orientation in the polymer film. Our findings provide a promising method for designing magnetic polymers and open avenues for spin-based applications utilizing organic materials.

Poly(3-hexylthiophene) (P3HT) is recognized as a conjugated polymer with a high optical excitation efficiency. Given this characteristic, preaggregation processes leveraging P3HT’s optical excitation have been extensively explored. In this study, we present a distinct preaggregation mechanism that depends on the wavelength of the irradiated light. The study involves irradiating the P3HT solution with various lights (red, green, blue, and UV) and subsequently analyzing the morphology of both the solution and the film through absorbance measurement, microscopy, and X-ray diffraction. The results indicate that irradiation with red and UV light enhances the charge transport properties of the P3HT films due to increased aggregation. Conversely, green and blue light irradiation results in diminished electrical performance and aggregation. Contrary to conventional expectations, our findings suggest that more than one mechanism may coexist in inducing preaggregation, depending on the wavelength. Specifically, UV light irradiation appears to increase the likelihood of excitation of tilted chains, thereby enhancing polymer linearity and promoting preaggregation. In contrast, red light irradiation predominantly induces excitation within the polymer crystals through π–π stacking interactions rather than along the polymer chains. This study provides that different excitation mechanisms are activated depending on the wavelength of the incident light and provides a systematic analysis of the distinct aggregation patterns observed.

Glycerol Oxidation In article number 2409082, Sanghan Lee and co-workers show the photoelectrochemical conversion of biomass-derived glycerol into glyceraldehyde, a high-value product used in pharmaceuticals as an antibiotic or anticancer agent and in other advanced industries. Using tungsten oxide photoelectrodes, glycerol is selectively oxidized with high efficiency, excellent durability, and sustained selectivity, enabled by the photo-stimulated self-recovery of the electrode surface.

Abstract Chiral optoelectronic materials capable of interacting with circularly polarized (CP) light have emerged as promising candidates for next‐generation technologies. This study presents a facile strategy for the preparation of chiroptical films by blending an achiral conjugated polymer, PDVT‐10, containing diketopyrrolopyrrole (DPP) moieties with chiral small molecules, 1,1′‐binaphthyl‐2,2′‐diamine (BN). Chirality induction in conjugated polymer systems is driven comprehensively from intermolecular hydrogen bonding to co‐crystallization with aggregation, as revealed by a stepwise approach of optical and X‐ray scattering analyses depending on the ratio. By optimizing the blending ratio of PDVT‐10 and BN to 7:3, near‐infrared (NIR)‐circularly polarized light‐sensitive phototransistors are successfully fabricated on 850 nm, which exhibit distinct CP light discrimination and photodetection performance. These findings provide insights into the mechanism of inducing chirality to achiral conjugated polymers, enhancing chiroptical properties, and providing applications in CP photosensitive optoelectronics.