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The achievement of high performance in organic solar cells (OSCs) is highly dependent on efficient exciton dissociation. However, a comprehensive understanding of the exciton dissociation process under photoexcitation in OSCs remains elusive. Herein, a prototypical system of PM6:Y6 is adopted to explore the exciton dissociation process. An organic semiconductor PCz with distinctive photoexcitation signals from PM6 and Y6 is incorporated as the third component. Femtosecond transient absorption spectroscopy demonstrates clear cascade charge transfer processes in ternary PM6:PCz:Y6 system. These cascade channels contribute to enhancing the efficiency of exciton dissociation. Consequently, the nonradiative recombination energy loss is reduced, resulting in an improved power conversion efficiency (PCE) of OSCs. Furthermore, the reduction of energy loss is verified in different OSCs. When PCz is introduced into the D18:L8‐BO system, a low nonradiative recombination energy loss of 0.175 eV is demonstrated, contributing a PCE of over 19%. This work highlights that the insight of efficient exciton dissociation enables low nonradiative recombination losses for efficient OSCs. [ABSTRACT FROM AUTHOR]

High‐boiling‐point solvents are considered to be decent solvents for the preparation of large‐area organic solar cells (OSCs) because of their wide processing window. However, the efficiency of OSCs processed by high‐boiling‐point solvents is still unsatisfactory. Herein, it is found that the agglomerate growth of nonfullerene acceptors into micrometer‐sized domains is the main reason for poor efficiency. A facile rapid molding process (RMP) scheme is proposed to solve this problem by adjusting the nucleation and growth behavior of acceptor molecules. RMP enables the blend films with interpenetrating networks and higher crystallinity, which is in favor of faster exciton separation and lower recombination losses. As a result, the power convention efficiency (PCE) is improved from 15.91% (reference) to 18.32% (RMP) for PL1:BTP‐eC9‐4F OSCs. To the best of the authors' knowledge, this is the champion efficiency of OSCs processed with high‐boiling‐point solvents. Meanwhile, RMP devices maintain 85% or 90% of the initial PCE after real day/night cycling in the air for over 2000 h or after continuous thermal aging at 85 °C in nitrogen for 500 h, respectively. [ABSTRACT FROM AUTHOR]

Although the advances in organic solar cells (OSCs) have been considerable, their efficiency is still limited by recombination losses. Photogenerated electrons and holes are generally bound as localized excitons in organic semiconductors. The transition from excitons into free charges requires diffusion and dissociation processes, in which parasitic recombination losses exist. Reducing these losses is necessary for highly efficient OSCs. The crystallization behavior of the active layers can influence the efficiency of exciton diffusion and dissociation. In this work, different additives are delicately designed to control the crystallization behavior. It is found that the crystallization quality of active layers can be improved by controlling the aggregation of nonfullerene acceptors. The π–π stacking of blend films becomes compact, meanwhile, the crystallization in the vertical direction is more uniform. These are beneficial to the diffusion and dissociation of excitons. As a consequence, recombination losses are reduced and power convention efficiencies (PCEs) are improved significantly. Meanwhile, the general applicability of the additive is demonstrated in various organic photovoltaic systems, in which a PCE of 19.3% is achieved in D18:BTP‐eC9‐4F OSCs. This work provides a facile strategy to reduce the recombination losses of excitons for efficient devices. [ABSTRACT FROM AUTHOR]

Nowadays, it is still a great challenge to obtain high‐performance green‐solvent‐processed organic solar cells (OSCs). In this study, a ternary blend strategy (one donor and two acceptors, 1D/2A) is developed to solve the difficulty of film morphology modulation during the fabrication of high‐performance green‐solvent‐processed OSCs. A typical high‐performance halogenated‐solvent processable binary system D18:BTP‐eC9‐4F is selected as the host, its green‐solvents‐processed devices show an inferior power conversion efficiency (PCE) of ≈16%. SM16 with two 3D shape persistent end groups is selected as the third component due to its high fluorescence quantum yield, reduced intermolecular interaction, good solubility, and moderate crystallinity. As a result, the ternary devices display bicontinuous interpenetrating networks, reduced energy loss, and suppressed charge carrier recombination losses. Hence, an excellent PCE of 18.20% is achieved for the D18:BTP‐eC9‐4F:SM16 ternary devices, which is much higher than D18:BTP‐eC9‐4F‐based binary ones and also one of the highest PCEs for the green‐solvents‐processed OSCs. Besides, this strategy also demonstrates a good universality for other binary systems and becomes an effective pathway for the development of green‐solvent processable high‐performance OSCs. [ABSTRACT FROM AUTHOR]

The research on perylene diimide (PDI) aggregates effectively promotes their applications in organic photovoltaic solar cells and fluorescent sensors. In this paper, a PDI fabricated with three peripheral PDI units (N, N'-bis(6-undecyl) perylene-3,4,9,10-bis(dicarboximide)) is investigated. The trimer shows different absorption and fluorescence properties due to hydrophobicity when dissolved in the mixed solvent of tetrahydrofuran (THF) and water. Through comprehensive analysis of the fluorescence lifetime and transient absorption spectroscopic results, we concluded that the trimer underwent different excited state kinetic pathways with different concentrations of water in THF. When dissolved in pure THF solvent, both the intramolecular charge-transfer and excimer states are formed. When the water concentration increases from 0 to 50% (v/v), the formation time of the excimer state and its structural relaxation time are prolonged, illustrating the arising of the intermolecular excimer state. It is interesting to determine that the probability of the intramolecular charge-transfer pathway will first decrease and then increase as the speed of intermolecular excimer formation slows down. The two inflection points appear when the water concentration is above 10% and 40%. The results not only highlight the importance of hydrophobicity on the aggregate properties of PDI multimers but also guide the further design of PDI-based organic photovoltaic solar cells. [ABSTRACT FROM AUTHOR]

In this work, inspired by the principles of a pressure cooker, we utilized a high‐pressure method to address the processing challenges associated with high molecular weight polymers. Through this approach, we successfully dissolved high molecular weight D18 in chloroform at 100 °C within a pressure‐tight vial. The increased steam pressure raised the boiling point and dissolving capacity of chloroform, enabling the creation of a hybrid film with superior properties, including more ordered molecular arrangement, increased crystallinity, extended exciton diffusion length, and improved phase morphology. Organic solar cells (OSCs) based on D18 : L8‐BO prepared using this high‐pressure method achieved an outstanding power conversion efficiency of 19.65 %, setting a new record for binary devices to date. Furthermore, this high‐pressure method was successfully applied to fabricate OSCs based on other common systems, leading to significant enhancements in device performance. In summary, this research introduces a universal method for processing high molecular weight D18 materials, ultimately resulting in the highest performance reported for binary organic solar cells. [ABSTRACT FROM AUTHOR]

In this work, inspired by the principles of a pressure cooker, we utilized a high‐pressure method to address the processing challenges associated with high molecular weight polymers. Through this approach, we successfully dissolved high molecular weight D18 in chloroform at 100 °C within a pressure‐tight vial. The increased steam pressure raised the boiling point and dissolving capacity of chloroform, enabling the creation of a hybrid film with superior properties, including more ordered molecular arrangement, increased crystallinity, extended exciton diffusion length, and improved phase morphology. Organic solar cells (OSCs) based on D18 : L8‐BO prepared using this high‐pressure method achieved an outstanding power conversion efficiency of 19.65 %, setting a new record for binary devices to date. Furthermore, this high‐pressure method was successfully applied to fabricate OSCs based on other common systems, leading to significant enhancements in device performance. In summary, this research introduces a universal method for processing high molecular weight D18 materials, ultimately resulting in the highest performance reported for binary organic solar cells. [ABSTRACT FROM AUTHOR]

[Display omitted] Porphyrin and perylene diimide have great application potential in organic optoelectronic devices. However, large plane frames of porphyrin and PDI tend to aggregate, resulting in low power conversion efficiency. In this work, four side chain modified porphyrins (H 2 TCPP, ZnTCPP, H 2 TCPP(CH 3) 4 , ZnTCPP(CH 3) 4), and one perylene diimide (PDI-C5) were synthesized. The blended films of the donor and acceptor were prepared by a simple and low-cost liquid deposition method. Femtosecond transient absorption spectroscopy and global analysis revealed that ZnTCPP(CH 3) 4 :PDI-C5 showed a higher rate of charge transfer and radical ions formation compared to the other porphyrin donors, which means that the ZnTCPP(CH 3) 4 has good compatibility with PDI-C5. In addition, we also characterized these blended films by ultraviolet–visible absorption spectroscopy, cyclic voltammetry (CV), and AFM techniques. The CV results show that the difference between the LUMO of each porphyrin donor and PDI-C5 acceptor is about 0.3 eV, which is sufficient for exciton dissociation. [ABSTRACT FROM AUTHOR]

Three terpolymer donors (PL1, PL2, and PL3) employing repeating units of two popular photovoltaic polymers PM6 and D18 are synthesized by random copolymerization. The terpolymers can reduce the regio‐regularity of the polymer backbones and endow them with much‐enhanced solubility in nonhalogenated solvents such as o‐xylene. Furthermore, along with the appearance of temperature‐dependent aggregation behavior, indicating the adaptability for fabricating organic solar cells (OSCs) by eco‐friendly solvent processing. Among them, PL1‐based OSCs display higher and more balanced hole and electron mobilities, longer charge separation exciton lifetime, and better exciton dissociation and charge collection capabilities than the parent polymers (PM6 and D18) based ones. A power conversion efficiency of 18.14% with a very low energy loss is achieved based on terpolymer PL1, which is much higher than that of PM6 (15.16%) and D18 (16.18%). The result provides an effective way to realize high‐performance nonhalogenated processing polymer donor materials. [ABSTRACT FROM AUTHOR]

Reducing non‐radiative energy loss (∆Enr) is critical for enhancing the photovoltaic performance of organic solar cells (OSCs). To achieve this, a small molecular donor, LJ1, is introduced as the third component in the host system D: A system (D18: BTP‐eC9‐4F). The cascade‐like energy level alignment of D18, LJ1, and BTP‐eC9‐4F facilitates efficient charge transfer. LJ1's good solubility in the processing solvent and high miscibility with BTP‐eC9‐4F delay the precipitation of BTP‐eC9‐4F, leading to improved phase morphology in blend films. Additionally, LJ1 increases spacing between the polymer donor (PD) and the small molecule acceptor (SMA), optimizing blend film morphology and reducing non‐radiative energy loss in OSCs. Ternary OSCs based on D18:LJ1:BTP‐eC9‐4F achieve a power conversion efficiency (PCE) of 19.43% with reduced ∆Enr. Notably, the ternary device using D18:LJ1:L8‐BO attains an outstanding PCE of 19.78%, which is one of the highest device efficiency for ternary OSC. The work highlights the effectiveness of the ternary blend strategy in enhancing OSC performance while minimizing ∆Enr. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is a non‐invasive treatment modality against a range of cancers and nonmalignant diseases, however one must be aware of the risk of causing phototoxic reactions after treatment. We herein report a bioinspired design of next‐generation photosensitizers (PSs) that not only effectively produce ROS but undergo fast metabolism after treatment to overcome undesirable side effects. We constructed a series of β‐pyrrolic ring‐opening seco‐chlorins, termed beidaphyrin (BP), beidapholactone (BPL), and their zinc(II) derivatives (ZnBP and ZnBPL), featuring intense near‐infrared absorption and effective O2 photosensitization. Irradiation of ZnBPL led to a non‐cytotoxic, metabolizable beidaphodiacetamide (ZnBPD) via in situ generated O2.− but not 1O2, as revealed by mechanistic studies including time‐resolved absorption, kinetics, and isotope labeling. Furthermore, water‐soluble ZnBPL showed an effective therapeutic outcome, fast metabolism, and negligible phototoxic reactions. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is a non‐invasive treatment modality against a range of cancers and nonmalignant diseases, however one must be aware of the risk of causing phototoxic reactions after treatment. We herein report a bioinspired design of next‐generation photosensitizers (PSs) that not only effectively produce ROS but undergo fast metabolism after treatment to overcome undesirable side effects. We constructed a series of β‐pyrrolic ring‐opening seco‐chlorins, termed beidaphyrin (BP), beidapholactone (BPL), and their zinc(II) derivatives (ZnBP and ZnBPL), featuring intense near‐infrared absorption and effective O2 photosensitization. Irradiation of ZnBPL led to a non‐cytotoxic, metabolizable beidaphodiacetamide (ZnBPD) via in situ generated O2.− but not 1O2, as revealed by mechanistic studies including time‐resolved absorption, kinetics, and isotope labeling. Furthermore, water‐soluble ZnBPL showed an effective therapeutic outcome, fast metabolism, and negligible phototoxic reactions. [ABSTRACT FROM AUTHOR]

• Phthalocyanines are one of the most widely studied organic semiconductor materials for decades. • A low-cost liquid deposition method is introduced to prepare phthalocyanine films. • The Q band of phthalocyanine films redshifted in the solid-state film compare to that in solution. • The aggregation caused by close packing in the solid film state had small influence on the decay of singlet excited state. Phthalocyanines (Pcs) are one of the most widely studied organic semiconductor materials, and many film fabrication methods have been developed and used in the Pcs film fabrication. Here, we introduced a low-cost liquid deposition method to prepare magnesium phthalocyanine (MgPc) film and characterized it using AFM, XRD, UV–vis absorption spectroscopy and femtosecond transient absorption spectroscopy. We found that the Q band of MgPc red-shifted in the solid-state film and the aggregation in the solid film state has a little influence on the decay of singlet excited state, but have a more significant impact on the non-radiative relaxation of the triplet state. [ABSTRACT FROM AUTHOR]

The ionic nature of organic trihalide perovskite leads to structural irregularity and energy disorder at the perovskite surface, which seriously affects the photovoltaic performance of perovskite solar cells. Here, the origin of the perovskite surface disorder is analyzed, and a facial ion‐exchange strategy is designed to regulate the surface chemical environment. By the reconstruction of terminal irregular Pb–I bonds and random cations, the repaired surface is characteristic of the reduced band tail states, consequent to the suppression of the uplift of quasi‐Fermi level splitting and photocarrier scattering. The optimized device gets a high open‐circuit voltage and operational stability. These findings fully elaborate the underlying mechanism concerning perovskite surface problem, giving guidance on tailoring the energy disorder. [ABSTRACT FROM AUTHOR]

The ternary strategy has proven to be an effective method for improving the efficiency of organic solar cells (OSCs). However, designing and selecting the third component still pose challenges. In this study, this issue is addressed by focusing on the PBDB‐T:Y18‐F binary system and introducing a new, strong luminescent, asymmetric small‐molecule acceptor (SMA) called L8‐CBIC‐Cl, which shares a similar skeleton with Y18‐F. The similarity in molecular framework facilitates good compatibility between the two acceptors, resulting in the formation of an alloy‐like acceptor phase. Furthermore, the norbornenyl‐modified end group in L8‐CBIC‐Cl contributes to its strong luminescent properties, which in turn leads to a low non‐radiative energy loss and a high open‐circuit voltage. Consequently, the PBDB‐T:L8‐CBIC‐Cl:Y18‐F based ternary devices realize a high power conversion efficiency (PCE) up to 17.01%, which is higher than PBDB‐T:Y18‐F device (14.49%). Importantly, L8‐CBIC‐Cl exhibits a good universality as a guest acceptor in other three binary systems (D18:Y6, D18:BTP‐eC9‐4F, and D18:L8‐BO). The D18:L8‐BO:L8‐CBIC‐Cl device shows an impressive efficiency of 19%. The work demonstrates that employing SMA with a high PLQY and better miscibility with host acceptor as the third component has a great potential for developing high‐efficiency ternary OSCs. [ABSTRACT FROM AUTHOR]

Utilizing intermolecular hydrogen‐bonding interactions stands for an effective approach in advancing the efficiency and stability of small‐molecule acceptors (SMAs) for polymer solar cells. Herein, we synthesized three SMAs (Qo1, Qo2, and Qo3) using indeno[1,2‐b]quinoxalin‐11‐one (Qox) as the electron‐deficient group, with the incorporation of a methylation strategy. Through crystallographic analysis, it is observed that two Qox‐based methylated acceptors (Qo2 and Qo3) exhibit multiple hydrogen bond‐assisted 3D network transport structures, in contrast to the 2D transport structure observed in gem‐dichlorinated counterpart (Qo4). Notably, Qo2 exhibits multiple and stronger hydrogen‐bonding interactions compared with Qo3. Consequently, PM6 : Qo2 device realizes the highest power conversion efficiency (PCE) of 18.4 %, surpassing the efficiencies of devices based on Qo1 (15.8 %), Qo3 (16.7 %), and Qo4 (2.4 %). This remarkable PCE in PM6 : Qo2 device can be primarily ascribed to the enhanced donor‐acceptor miscibility, more favorable medium structure, and more efficient charge transfer and collection behavior. Moreover, the PM6 : Qo2 device demonstrates exceptional thermal stability, retaining 82.8 % of its initial PCE after undergoing annealing at 65 °C for 250 hours. Our research showcases that precise methylation, particularly targeting the formation of intermolecular hydrogen‐bonding interactions to tune crystal packing patterns, represents a promising strategy in the molecular design of efficient and stable SMAs. [ABSTRACT FROM AUTHOR]

Utilizing intermolecular hydrogen‐bonding interactions stands for an effective approach in advancing the efficiency and stability of small‐molecule acceptors (SMAs) for polymer solar cells. Herein, we synthesized three SMAs (Qo1, Qo2, and Qo3) using indeno[1,2‐b]quinoxalin‐11‐one (Qox) as the electron‐deficient group, with the incorporation of a methylation strategy. Through crystallographic analysis, it is observed that two Qox‐based methylated acceptors (Qo2 and Qo3) exhibit multiple hydrogen bond‐assisted 3D network transport structures, in contrast to the 2D transport structure observed in gem‐dichlorinated counterpart (Qo4). Notably, Qo2 exhibits multiple and stronger hydrogen‐bonding interactions compared with Qo3. Consequently, PM6 : Qo2 device realizes the highest power conversion efficiency (PCE) of 18.4 %, surpassing the efficiencies of devices based on Qo1 (15.8 %), Qo3 (16.7 %), and Qo4 (2.4 %). This remarkable PCE in PM6 : Qo2 device can be primarily ascribed to the enhanced donor‐acceptor miscibility, more favorable medium structure, and more efficient charge transfer and collection behavior. Moreover, the PM6 : Qo2 device demonstrates exceptional thermal stability, retaining 82.8 % of its initial PCE after undergoing annealing at 65 °C for 250 hours. Our research showcases that precise methylation, particularly targeting the formation of intermolecular hydrogen‐bonding interactions to tune crystal packing patterns, represents a promising strategy in the molecular design of efficient and stable SMAs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synthesis is simple and the reaction yield of each step is about 80%. • Devices based on nonfused ring electron acceptors show high efficiency. • π-Bridge unit determines photovoltaic behavior of nonfused ring electron acceptors. Due to the advantages of simple synthesis and low cost, fully nonfused ring electron acceptors (FN-FREAs) have been developed in recent years. Almost all reported FN-FREAs use thiophene derivatives as π-bridging unit, while other π-bridging units have not yet been developed. Here, an FN-FREA M01 with 2,5-bis(alkyloxy)phenylene as the π-bridge unit is designed and synthesized to compare its photovoltaic property with an analogue M05 which uses 3,4-bis(alkyloxy)thiophene as the π-bridge unit. Although the only variation between M01 and M05 is the π-bridge unit, these two FN-FREAs demonstrate significantly different photovoltaic performances. Organic solar cells (OSCs) based on M01 exhibit a high power conversion efficiency of 13.70%, while M05 based one shows a much lower efficiency of 3.96% with a markedly reduced short-circuit current density. Fluorescence, Raman, electron paramagnetic resonance, and femtosecond time-resolved transient absorption spectroscopy prove that M05 tends to be oxidized to form radical cations which aggravates exciton quenching and charge carrier recombination in the active layer, while in M01 such radical cations are absent. All in all, we have demonstrated that the π-bridging unit of FN-FREAs is pivotal to the photovoltaic performance and provided a useful design strategy to low-cost, high-efficiency, and chemically stable acceptor materials. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: By simplifying the π‐bridge unit, a nonfused ring electron acceptor (NFREA) BM‐2F was designed and synthesized with several high‐yield steps. The specific molecular structure features of BM‐2F are planar molecular backbone and out‐of‐plane side chain, which is favorable for charge transport and can suppress the over‐aggregation. BM‐2F based neat and blend films display obvious face‐on molecular orientation. Specially, D18:BM‐2F based blend film can form good bicontinuous interpenetrating network. More excitingly, a power conversion efficiency of 16.15% was achieved with D18:BM‐2F based photovoltaic devices, which is the highest one based on NFREAs. Our researches manifest that NFREA is a promising direction for low‐cost and high‐performance organic solar cells. [ABSTRACT FROM AUTHOR]

Transient absorption (TA) spectroscopy is a powerful technique for studying ultrafast processes in physics, chemistry, biology, and materials. It is challenging to obtain high-quality TA spectra when there is severe light scattering in the sample. We propose an experimental approach to completely remove all noise caused by pump scattering in TA spectra using phase and amplitude modulation. We demonstrate through theoretical analysis and experiments that this method can remove the additive noise and convolution noise, all the noise in TA caused by pump scattering. [ABSTRACT FROM AUTHOR]