Sung Jae Jeon

Achieving high efficiency and long‐term stability under ambient processing conditions remains a critical hurdle for the commercialization of organic solar cells (OSCs). Here, we report two new Y6‐analogs—BT(BO)‐ v ‐T(C12)‐4F (4F) and BT(BO)‐ v ‐T(C12)‐4Cl (4Cl)—featuring vinylene ( v )‐bridged DA′D cores, designed to improve the material's scalability while maintaining the structural advantages of Y6‐type acceptors. Morphological and device‐level investigations reveal that these M‐Y6 derivatives facilitate thermodynamically stable molecular packing and favorable crystalline orientation, even when fully processed in air. Incorporation of 4F into a layer‐by‐layer ternary architecture with D18/L8‐BO via a reproducible air‐processing protocol results in a certified power conversion efficiency (PCE) of 19%, among the highest reported for conventional OSCs fabricated under ambient conditions. Moreover, 4F‐based devices demonstrate exceptional thermal and photostability, retaining over 80% of their initial PCE after extended aging under the ISOS‐L‐1 protocol without encapsulation. These improvements are attributed to the enhanced crystallinity, vertical molecular alignment, and morphological robustness imparted by the 4F acceptor. This study identifies BT(BO)‐ v ‐T(C12)‐4F as a promising air‐processable acceptor for scalable OSCs that combine high efficiency with long‐term operational durability.

Organic photovoltaics (OPVs) have recently surpassed 20% power conversion efficiency (PCE), highlighting their potential for commercial application. However, their widespread adoption remains hindered by the high cost of photoactive materials and reliance on toxic halogenated solvents. Here, we report the design and synthesis of a cost-effective acceptor unit, 2-ethylhexyl 2,5-bis(5-bromoselenophen-2-yl)benzoate (SeBnCOOEH), accessible via a concise four-step synthesis from low-cost, commercially available precursors. Incorporation of this unit into donor polymers yields P(F2DBDT-SeBnCOOEH) and a terpolymer PM6(SeBnCOOEH = 0.15), both exhibiting enhanced solubility in the environmentally benign solvent toluene (TL) compared to the reference polymer PM6. Remarkably, the terpolymer effectively displays temperature-dependent aggregation behavior in solution, enabling favorable phase separation and optimized blend morphology in active layers. As a result, TL-processed OPV devices based on PM6(SeBnCOOEH = 0.15) achieve a notable PCE of 17.81%, representing one of the highest efficiencies reported for TL-processed systems. This work introduces a rational molecular design strategy that simultaneously addresses material cost and processing sustainability, advancing the development of high-performance OPVs compatible with green solvent systems.

Organic solar cells (OSCs) are made from carbon-rich organic compounds with low environmental impacts, unlike the silicon in traditional solar panels. Some of these organic materials can be broken down and reprocessed, enabling the recovery of valuable components. Specifically, the active-layer materials that make up OSCs can be designed with sustainability in mind. However, it is important to note that practical active materials that can be used for the commercialization of OSCs are still an area of research and development due to their low efficiency/stability and processability. Herein, we designed and synthesized three A-D-A’-D-A-type long-conjugated non-fullerene acceptors (NFAs) by incorporating various electron-withdrawing groups into the benzothiadiazole-diindacenodithiophene core. These NFAs, by changing their end-capping groups, exhibit not only distinct physical, optical, and electrochemical properties, but also differences in crystallinity and exciton dissociation. As a result, they exhibited significant differences in photovoltaic performance in PM6 donor-based binary devices. The introduction of small amounts of NFAs as a third component in the PM6:BTP-eC9 blend significantly enhanced its photon harvesting capabilities and influenced its charge transfer dynamics. Finally, we achieved a remarkable power conversion efficiency of nearly 17% by utilizing an eco-friendly solvent. This study provides valuable insights for the development of NFAs in efficient and eco-friendly OSCs.

Piperazine‐2,5‐dione (glycine anhydride, GA) has recently emerged as a valuable precursor for high‐performance π‐conjugated polymer semiconductors in organic electronics. We utilized GA to design a novel bisindolin‐dihydropiperazine (IDHP)‐based conjugated polymer, PIDHPTT, for aqueous chemical sensing. In the isatin‐flanked monomer, GA exists as a non‐conjugated lactam (DHP‐NH) but converts to a conjugated lactim (DHP‐OH) form within the polymer. Density functional theory (DFT) calculations show that this conversion is driven by energy minimization via extended π‐conjugation. Neighboring DHP units in the lactim form facilitate this process through π‐bridges, demonstrating a vinylogous effect, which has previously only been observed in small molecules. This is the first study to report such a long‐range vinylogous effect in a polymer due to the collective synergy of numerous functional groups. The OH groups in the lactim DHP interact more strongly with fluoride ions than other halides. PIDHPTT exhibits significant changes in optical absorption, electrochemical impedance, and charge transport in response to fluoride ions, which differ from responses to other halides. A water‐gated organic field‐effect transistor based on PIDHPTT shows excellent sensitivity and selectivity for fluoride ions, demonstrating the potential of this polymer design for chemical sensing applications.

Piperazine‐2,5‐dione (glycine anhydride, GA) has recently emerged as a valuable precursor for high‐performance π‐conjugated polymer semiconductors in organic electronics. We utilized GA to design a novel bisindolin‐dihydropiperazine (IDHP)‐based conjugated polymer, PIDHPTT, for aqueous chemical sensing. In the isatin‐flanked monomer, GA exists as a non‐conjugated lactam (DHP‐NH) but converts to a conjugated lactim (DHP‐OH) form within the polymer. Density functional theory (DFT) calculations show that this conversion is driven by energy minimization via extended π‐conjugation. Neighboring DHP units in the lactim form facilitate this process through π‐bridges, demonstrating a vinylogous effect, which has previously only been observed in small molecules. This is the first study to report such a long‐range vinylogous effect in a polymer due to the collective synergy of numerous functional groups. The OH groups in the lactim DHP interact more strongly with fluoride ions than other halides. PIDHPTT exhibits significant changes in optical absorption, electrochemical impedance, and charge transport in response to fluoride ions, which differ from responses to other halides. A water‐gated organic field‐effect transistor based on PIDHPTT shows excellent sensitivity and selectivity for fluoride ions, demonstrating the potential of this polymer design for chemical sensing applications.

The dissemination of sensors is key to realizing a sustainable, ‘intelligent’ world, where everyday objects and environments are equipped with sensing capabilities to advance the sustainability and quality of our lives—e.g. via smart homes, smart cities, smart healthcare, smart logistics, Industry 4.0, and precision agriculture. The realization of the full potential of these applications critically depends on the availability of easy-to-make, low-cost sensor technologies. Sensors based on printable electronic materials offer the ideal platform: they can be fabricated through simple methods (e.g. printing and coating) and are compatible with high-throughput roll-to-roll processing. Moreover, printable electronic materials often allow the fabrication of sensors on flexible/stretchable/biodegradable substrates, thereby enabling the deployment of sensors in unconventional settings. Fulfilling the promise of printable electronic materials for sensing will require materials and device innovations to enhance their ability to transduce external stimuli—light, ionizing radiation, pressure, strain, force, temperature, gas, vapours, humidity, and other chemical and biological analytes. This Roadmap brings together the viewpoints of experts in various printable sensing materials—and devices thereof—to provide insights into the status and outlook of the field. Alongside recent materials and device innovations, the roadmap discusses the key outstanding challenges pertaining to each printable sensing technology. Finally, the Roadmap points to promising directions to overcome these challenges and thus enable ubiquitous sensing for a sustainable, ‘intelligent’ world.

Dicyanobenzene (DCB), a weak Lewis base, effectively passivates perovskite films by eliminating residual PbI₂, enhancing crystallinity, and reducing trap state density, thus enhancing perovskite solar cell performance and stability.

The development of eco‐friendly solvent‐processed organic solar cells (OSCs) suitable for industrial‐scale production should be now considered the imperative research. Herein, asymmetric 3‐fluoropyridine (FPy) unit is used to control the aggregation and fibril network of polymer blends. Notably, terpolymer PM6(FPy = 0.2) incorporating 20% FPy in a well‐known donor polymer poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl‐3‐fluoro)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b’]dithiophene))‐alt‐(5,5‐(1’,3’‐di‐2‐thienyl‐5’,7’‐bis(2‐ethylhexyl)benzo[1’,2’‐c:4’,5’‐c’]dithiophene‐4,8‐dione)] (PM6) can reduce the regioregularity of the polymer backbone and endow them with much‐enhanced solubility in eco‐friendly solvents. Accordingly, the excellent adaptability for fabricating versatile devices based on PM6(FPy = 0.2) by toluene processing is demonstrated. The resulting OSCs exhibit a high power conversion efficiency (PCE) of 16.1% (17.0% by processed with chloroform) and low batch‐to‐batch variation. Moreover, by controlling the donor‐to‐acceptor weight ratio at 0.5:1.0 and 0.25:1.0, semi‐transparent OSCs (ST‐OSCs) yield significant light utilization efficiencies of 3.61% and 3.67%, respectively. For large‐area (1.0 cm²) indoor OSC (I‐OSC), a high PCE of 20.6% is achieved with an appropriate energy loss of 0.61 eV under a warm white light‐emitting diode (3,000 K) with the illumination of 958 lux. Finally, the long‐term stability of the devices is evaluated by investigating their structure–performance–stability relationship. This work provides an effective approach to realizing eco‐friendly, efficient, and stable OSCs/ST‐OSCs/I‐OSCs.