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Layer‐by‐layer (LbL) deposition of active layers in organic solar cells (OSCs) offers immense potential for optimizing performance through precise tailoring of each layer. However, achieving high‐performance LbL OSCs with distinct solid additives in each layer remains challenging. In this study, we explore a novel approach that strategically incorporates different solid additives into specific layers of LbL devices. To this end, we introduce FeCl3 into the lower donor (D18) layer as a p‐type dopant to enhance hole concentration and mobility. Concurrently, we incorporate the wide‐band gap conjugated polymer poly(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl) (PFO) into the upper acceptor (L8‐BO) layer to improve the morphology and prolong exciton lifetime. Unlike previous studies, our approach combines these two strategies to achieve higher and more balanced electron and hole mobility without affecting device open‐circuit voltage, while also suppressing charge recombination. Consequently, the power conversion efficiency (PCE) of the D18+FeCl3/L8‐BO device increases to 18.12 %, while the D18/L8‐BO+PFO device attains a PCE of 18.79 %. These values represent substantial improvements over the control device′s PCE of 17.59 %. Notably, when both FeCl3 and PFO are incorporated, the D18+FeCl3/L8‐BO+PFO device achieves a remarkable PCE of 19.17 %. In summary, our research results demonstrate the effectiveness of the layered solid additive strategy in improving OSC performance. [ABSTRACT FROM AUTHOR]

Designing and synthesizing narrow band gap acceptors that exhibit high photoluminescence quantum yield (PLQY) and strong crystallinity is a highly effective, yet challenging, approach to reducing non‐radiative energy losses (▵Enr) and boosting the performance of organic solar cells (OSCs). We have successfully designed and synthesized an A–D–A type fused‐ring electron acceptor, named DM‐F, which features a planar molecular backbone adorned with bulky three‐dimensional camphane side groups at its central core. These bulky substituents effectively hinder the formation of H‐aggregates of the acceptors, promoting the formation of more J‐aggregates and notably elevating the PLQY of the acceptor in the film. As anticipated, DM‐F showcases pronounced near‐infrared absorption coupled with impressive crystallinity. Organic solar cells (OSCs) leveraging DM‐F exhibit a high EQEEL value and remarkably low ▵Enr of 0.14 eV‐currently the most minimal reported value for OSCs. Moreover, the power conversion efficiency (PCE) of binary and ternary OSCs utilizing DM‐F has reached 16.16 % and 20.09 %, respectively, marking a new apex in reported efficiency within the OSCs field. In conclusion, our study reveals that designing narrow band gap acceptors with high PLQY is an effective way to reduce ▵Enr and improve the PCE of OSCs. [ABSTRACT FROM AUTHOR]

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]

The side‐chain has a significant influence on the optical properties and aggregation behaviors of the organic small molecule acceptors, which becomes an important strategy to optimize the photovoltaic performance of organic solar cells. In this work, we designed and synthesized three brand‐new nonfused ring electron acceptors (NFREAs) OC4‐4Cl‐Ph, OC4‐4Cl‐Th, and OC4‐4Cl‐C8 with hexylbenzene, hexylthiophene, and octyl side chains on the π‐bridge units. Compared with OC4‐4Cl‐Ph and OC4‐4Cl‐Th, OC4‐4Cl‐C8 with linear alkyl side chain has more red‐shift absorption, which is conducive to obtaining higher short‐circuit current density. Additionally, the OC4‐4Cl‐C8 film exhibits a longer exciton diffusion distance, and the D18:OC4‐4Cl‐C8 blend film displays faster hole transfer, weaker bimolecular recombination, and more efficient exciton transport. Furthermore, The D18:OC4‐4Cl‐C8 blend films may effectively form interpenetrating networks that resemble nanofibrils, which can facilitate exciton dissociation and charge transport. Finally, OC4‐4Cl‐C8‐based devices can be created a marvellously power conversion efficiency (PCE) of 16.56%, which is much higher than OC4‐4Cl‐Ph (12.29%)‐ and OC4‐4Cl‐Th‐based (11.00%) ones, being the highest PCE among the NFREA based binary devices. All in all, we have validated that side‐chain engineering is an efficient way to achieve high‐performance NFREAs. [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]

Non‐fullerene acceptors have shown great promise for organic solar cells (OSCs). However, challenges in achieving high efficiency molecular system with conformational unicity and effective molecular stacking remain. In this study, we present a new design of non‐fused tetrathiophene acceptor R4T‐1 via employing the encapsulation of tetrathiophene with macrocyclic ring. The single crystal structure analysis reveals that cyclic alkyl side chains can perfectly encapsulate the central part of molecule and generate a conformational stable and planar molecular backbone. Whereas, the control 4T‐5 without the encapsulation restriction displays cis‐ and twisted conformation. As a result, R4T‐1 based OSCs achieved an outstanding power conversion efficiency (PCE) exceeding 15.10 % with a high short‐circuit current density (Jsc) of 25.48 mA/cm2, which is significantly improved by ≈30 % in relative to that of the control. Our findings demonstrate that the macrocyclic encapsulation strategy could assist fully non‐fused electron acceptors (FNEAs) to achieve a high photovoltaic performance and pave a new way for FNEAs design. [ABSTRACT FROM AUTHOR]

A series of wide bandgap (WBG) conjugated polymers PTFBDT‐C, PTFBDT‐O and PTFBDT‐S are designed and synthesized with alkyl, alkoxy and thioalkyl side chains. By selecting benzodithiophene derivatives as the donor units and benzothiadiazole derivatives as the acceptor units, PTFBDT‐C, PTFBDT‐O and PTFBDT‐S are all of wide optical bandgaps. Furthermore, low bandgap small molecule L8‐BO‐4F is used as the acceptor to fabricate organic solar cells (OSCs). According to the results, PTFBDT‐C:L8‐BO‐4F blend film displays appropriate phase separation, high hole and electron mobilities, etc. Thus, the power conversion efficiency (PCE) of PTFBDT‐C:L8‐BO‐4F based OSCs is 14.02%, which is much higher than those of PTFBDT‐O:L8‐BO‐4F based (9.06%) and PTFBDT‐S:L8‐BO‐4F based ones (10.45%). These results show that the side chain engineering is an effective strategy to improve photovoltaic performance of wide bandgap polymers. [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]

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]

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]

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]

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]

Planar building block B2TCl with C2V symmetry configuration is designed to prepare polymer donors (PB2TCl‐o and PB2TCl‐i) with good solubility in non‐halogenated solvents. When blended with BTP‐ec9‐4F, PB2TCl‐o‐based devices processed by 1,2‐dimethylbenzene (o‐DMB) give a power conversion efficiency (PCE) of 15.10% with a Voc of 0.89 V, a Jsc of 24.37 mA cm–2, and an fill factor of 69.69%. Semitransparent OSCs based on PB2TCl‐o:BTP‐ec9‐4 can afford a PCE of 9.09% with an average visible transmittance (AVT) of 23.9% and an AT of 24.2%. B2TCl‐o is also used as a third component to prepare random terpolymers PW1 and PW2. Using o‐DMB as the processing solvent, PW1 and PW2‐based devices give improved PCEs of 16.26% and 17.19%, respectively, which are much higher than the parent polymers (PM6 and D18). This work provides a versatile building block B2TCl‐o for the preparation of non‐halogen solvent processable high‐performance polymer donor materials. [ABSTRACT FROM AUTHOR]

Increasing the photoluminescence quantum yield (PLQY) of narrow bandgap acceptors is of critical importance to suppress the nonradiative voltage loss (ΔVnr) in organic solar cells (OSCs). Herein, two acceptors, SM16 and SM16‐R, with an identical backbone but different terminal groups (norbornenyl modified 1,1‐dicyanomethylene‐3‐indanone and dimethyl substituted 1,1‐dicyanomethylene‐3‐indanone) are designed and synthesized. Compared with SM16‐R, SM16 displays better solubility, higher PLQY, and more favorable nanomorphology when blended with polymer donor PBDB‐T. PBDB‐T:SM16‐based OSCs yield a ΔVnr as low as 0.145 V. Using SM16 as the third component, a high power conversion efficiency of 17.1% is achieved in the ternary OSCs based on PBDB‐T:Y14:SM16, considerably higher than that of the binary devices based on PBDB‐T:Y14 or PBDB‐T:SM16. These results highlight that enhancing the PLQY of low bandgap acceptor via terminal group engineering strategy is highly effective to reduce ΔVnr of OSCs. [ABSTRACT FROM AUTHOR]

A perylene diimide (PDI) derivative was used as the third component to prepare high‐efficiency ternary organic solar cells (OSCs). PDI derivatives usually bear a wide bandgap and a long exciton diffusion length, which could be helpful to promote the device efficiency and still retain a high open‐circuit voltage (Voc). Compared with the binary OSC, the photovoltaic performance improved. Further changing the method for preparing the processing solutions from dissolving the polymer donor and small‐molecule acceptor ITTC together to dissolving them individually, molecular packing in the deposited active layer could be adjusted and the short‐circuit current density could be increased. As a result, the final device efficiency in such OSCs achieved 12.29 % power conversion efficiency (PCE) with a high Voc of 0.93 V. When using the PDI derivative as the third component to D18 : BTP‐eC9‐based OSCs, a high PCE of 17.38 % was obtained, which is the best one among photovoltaic devices employing PDI derivatives. [ABSTRACT FROM AUTHOR]

Three nonfused ring electron acceptors (NFREAs; 2Th‐2F, BTh‐Th‐2F, and 2BTh‐2F) with thieno[3,2‐b]thiophene bearing two bis(4‐butylphenyl)amino substituents as the core, 3‐octylthiophene or 3‐octylthieno[3,2‐b]thiophene as the spacer, and 3‐(1,1‐dicyanomethylene)‐5,6‐difluoro‐1‐indanone as the terminal group are designed and synthesized. The molar extinction coefficient of acceptors and the electron mobility of blend films gradually increase with increasing π‐conjugation length. Moreover, 2BTh‐2F displays a planar molecular conformation assisted by S···N and S···O intramolecular interactions. More importantly, the molecular stacking changes from 2D packing for the 2Th‐2F analog to 3D network packing for 2BTh‐2F. Due to these comprehensive merits, 2BTh‐2F:PBDB‐T‐based organic solar cells give a high power conversion efficiency of 14.53%. More impressively, when D18 is used as the donor polymer, the power conversion efficiency is further enhanced to 15.44%, which is the highest value reported for solar cells based on NFREAs. [ABSTRACT FROM AUTHOR]

Ternary strategy has been demonstrated to be an effective way to improve power conversion efficiency (PCE) of single‐junction organic solar cells (OSCs). Herein, high‐efficiency ternary OSCs are fabricated based on the PBDB‐T:DO‐2F binary system and acceptor IDTT‐OB with asymmetric side chains as the third component. The introduction of nonfullerene acceptors (NFAs) IDTT‐OB as a third component can efficiently increase the compatibility of the ternary system, reduce the crystallinity of DO‐2F, optimize the blend film morphology, improve the charge transport and collection, suppress the bimolecular recombination, and reduce the nonradiative energy loss (ΔEnonrad). Finally, the PBDB‐T:DO‐2F:IDTT‐OB‐based ternary device exhibits a high PCE of 14.09% with Voc of 0.87 V, Jsc of 21.47 mA cm−2, and fill factor of 75.70%, which is about 30% higher than the corresponding PBDB‐T:DO‐2F‐ and PBDB‐T:IDTT‐OB‐based binary devices. Meanwhile, the ternary device also achieves a very low ΔEnonrad of 0.22 eV. This work indicates that the ternary strategy can effectively optimize morphology of active layer, reduce nonradiative energy loss, and further improve photovoltaic performance of OSCs. [ABSTRACT FROM AUTHOR]

Three asymmetric non‐fullerene acceptors (LL2, LL3, and LL4) are designed and synthesized with one norbornyl‐modified 1,1‐dicyanomethylene‐3‐indanone (CBIC) terminal group and one chlorinated 1,1‐dicyanomethylene‐3‐indanone (IC‐2Cl) terminal group. The three‐dimensional shape‐persistent CBIC terminal group can effectively enhance the solubility and tune the packing mode of acceptors. Compared with their symmetric counterparts (LL2‐2Cl, LL3‐2Cl, and LL4‐2Cl) bearing two IC‐2Cl terminals, the asymmetric acceptors show improved solubilities, giving rise to enhanced crystallinity and favored nanomorphology for charge transport in the blend films with PBDB‐T. Asymmetric acceptors based organic solar cells (OSCs) also show much lower voltage loss due to their higher ECT and EQEEL values. Therefore, they exhibit 17−27% higher power conversion efficiency (PCE) than OSCs based on the corresponding symmetric acceptors. Among these six acceptors, LL3 with a central benzotriazole core shows the best PCE of 16.82% with an outstanding Jsc of 26.97 mA cm−2 and a low nonradiative voltage loss (ΔVnr) of 0.18 V, the best values for PBDB‐T based OSCs. The Jsc and ΔVnr also represent the best reported for asymmetric non‐fullerene acceptors‐based OSCs to date. The results demonstrate that the combination of the unique CBIC terminal group with the asymmetric strategy is a promising way to enhance the performance of OSCs. [ABSTRACT FROM AUTHOR]

A series of tetrathiophene‐based fully non‐fused ring acceptors (4T‐1, 4T‐2, 4T‐3, and 4T‐4), which can be paired with the star donor polymer PBDB‐T to fabricate highly efficient organic solar cells are developed. Tailoring the size of lateral chains can tune the solubility and packing mode of acceptor molecules in neat and blend films. It is found that the incorporation of 2‐ethylhexyl chains can effectively change the compatibility with the donor polymer PBDB‐T, and an encouraging power conversion efficiency of 10.15% is accomplished by 4T‐3‐based organic solar cells. It also presents good compatibility with the other polymer donor and an even higher power conversion efficiency (PCE) of 12.04% is achieved based on D18:4T‐3 blend, which is the champion PCE for the fully non‐fused acceptors. Importantly, these inexpensive tetrathiophene fully non‐fused ring acceptors provide cost‐effective photovoltaic performance. The results demonstrate a high photovoltaic performance from synthetically inexpensive materials could be achieved by the rational design of non‐fused ring acceptor molecules. [ABSTRACT FROM AUTHOR]

Fused‐ring electron acceptors have made significant progress in recent years, while the development of fully non‐fused ring acceptors has been unsatisfactory. Here, two fully non‐fused ring acceptors, o‐4TBC‐2F and m‐4TBC‐2F, were designed and synthesized. By regulating the location of the hexyloxy chains, o‐4TBC‐2F formed planar backbones, while m‐4TBC‐2F displayed a twisted backbone. Additionally, the o‐4TBC‐2F film showed a markedly red‐shifted absorption after thermal annealing, which indicated the formation of J‐aggregates. For fabrication of organic solar cells (OSCs), PBDB‐T was used as a donor and blended with the two acceptors. The o‐4TBC‐2F‐based blend films displayed higher charge mobilities, lower energy loss and a higher power conversion efficiency (PCE). The optimized devices based on o‐4TBC‐2F gave a PCE of 10.26 %, which was much higher than those based on m‐4TBC‐2F at 2.63 %, and it is one of the highest reported PCE values for fully non‐fused ring electron acceptors. [ABSTRACT FROM AUTHOR]

Herein, a novel wide‐band‐gap donor polymer, PBTVT, which comprises a bis(carboxylic ester)‐substituted thiophene–vinylene–thiophene (TVT) acceptor unit and benzodithiophene donor unit, is designed and synthesized. PBTVT displays good solubility in halogen‐free green solvents such as o‐xylene at elevated temperature. Grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) measurement revealed that PBTVT can form the desired face‐on orientation in the blend films. Organic solar cells are fabricated with PBTVT as the donor and ITOIC‐2F as the acceptor. Although the highest occupied molecular orbital (HOMO) level offset between PBTVT and 2,2′‐((2Z,2′Z)‐(((4,4,9,9‐tetrakis(4‐hexylphenyl)‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,7‐diyl)bis(3,4‐bis(hexyloxy)thiophene‐5,2‐diyl))bis(methanylylidene))bis(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (ITOIC‐2F) is only 0.08 eV, devices still exhibit an overall power conversion efficiency (PCE) of 11.04%. Especially, devices fabricated with the green solvent o‐xylene outperform those fabricated with halogenated solvents such as 1,2‐dichlorobenzene (o‐DCB). [ABSTRACT FROM AUTHOR]

Herein, norbornyl (NB), a bulky annular nonconjugated spacer, is melded into π systems to construct two groups of ladder‐type room‐temperature phosphorescence (RTP) luminogens. The effect of the NB on π‐π interactions, packing modes and RTP performance is explored systematically. The experimental and computational results demonstrate the versatility of NB in reducing π‐π distances and synergistically intensifying the intermolecular interactions, which not only induces intersystem crossing from S1 to Tn but also diminishes the nonradiative decay of triplet excitons. Impressively, 1800‐fold phosphorescence lifetime enhancement is achieved in comparison with the reference compounds without NB. The molecular packing and RTP performance can be further modulated by the length of the backbones and terminal end‐groups. It is quite peculiar that NB‐annulated phthalic acid exhibits reversible photochromism in the solid state, likely due to the formation of persistent radical pairs. Our study paves an ingenious avenue towards enhancing intermolecular interactions and provides significant implications for a better comprehensive understanding of the origin of their RTP and the inherent photophysical mechanism. [ABSTRACT FROM AUTHOR]

Abstract: Molecular engineering of nonfullerene acceptors (NFAs) plays a vital role in the development of organic photovoltaics. Oxygen as an electron donating atom is incorporated into the NFA system as alkoxyl forms at central, terminal, or central conjugated moieties due to the tunability at structural conformation, solubility, electron donating ability, absorption, energy levels, etc. In this work, a novel dipyran‐based ladder‐type building block (Ph‐DTDP), which possesses two oxygen atoms in the conjugated skeleton, is designed and facilely synthesized. It is applied as the donor core for the acceptor–donor–acceptor‐type NFA design and such functionalized‐O efficiently enhances the electron donating ability, lowers the band gap, redshifts and extends the absorption spectra. In addition, the π‐bridge effects are considered as well. Photovoltaic performances are systematically investigated and a high power conversion efficiency of 9.21% can be afforded with an energy loss of 0.57 eV. Meanwhile, the morphologies as well as the carrier mobilities of the blend films are studied to assist further understanding of the structure–property relationships. Overall, the study in this work provides a new promising ladder‐type dipyran building block and brings in a novel way to use oxygen in NFA molecular structure design. [ABSTRACT FROM AUTHOR]

Herein a H2S sensor based on a polymer field-effect transistor is reported and the sensor shows high sensitivity, excellent selectivity, fast response, and good operational stability. A concentration as low as 1 ppb H2S is detectable, which is to date the most sensitive H2S sensor based on organic semiconducting film. Thinning the thickness of active layer does not necessarily improve the sensitivity, but rather leads to the reduction of performance if the thickness is too low. Further analysis proposes a mechanism that the changing rate of absorption and desorption of H2S molecules is different when the thickness of active layer varies, indicating the necessity for thickness optimization. [ABSTRACT FROM AUTHOR]

Performance enhancement of polymer solar cells (PSCs) is achieved by expanding the absorption of the active layer of devices. To better match the spectrum of solar radiation, two polymers with different band gaps are used as the donor material to fabricate ternary polymer cells. Ternary blend PSCs exhibit an enhanced short-circuit current density and open-circuit voltage in comparison with the corresponding HD-PDFC-DTBT (HD)- and DT-PDPPTPT (DPP)-based binary polymer solar cells, respectively. Ternary PSCs show a power conversion efficiency (PCE) of 6.71%, surpassing the corresponding binary PSCs. This work demonstrates that the fabrication of ternary PSCs by using two polymers with complementary absorption is an effective way to improve the device performance. [ABSTRACT FROM AUTHOR]

High-molecular-weight conjugated polymer HD-PDFC-DTBT with N-(2-hexyldecyl)-3,6-difluorocarbazole as the donor unit, 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit, and thiophene as the spacer is synthesized by Suzuki polycondensation. HD-PDFC-DTBT shows a large bandgap of 1.96 eV and a high hole mobility of 0.16 cm2 V−1 s−1. HD-PDFC-DTBT:PC71BM-based inverted polymer solar cells (PSCs) give a power conversion efficiency (PCE) of 7.39% with a Voc of 0.93 V, a Jsc of 14.11 mA cm−2, and an FF of 0.56. [ABSTRACT FROM AUTHOR]

A new donor-acceptor-acceptor (D-A-A) type of conjugated molecule, N-(4-( N′, N′-diphenyl)phenylamine)-4-(4′-(2,2-dicyanovinyl)phenyl) naphthalene-1,8-dicarboxylic monoimide ( TPA-NI-DCN), consisting of triphenylamine (TPA) donors and naphthalimide (NI)/dicyanovinylene (DCN) acceptors was synthesized and characterized. In conjunction with previously reported D-A based materials, the additional DCN moiety attached as end group in the D-A-A configuration can result in a stable charge transfer (CT) and charge-separated state to maintain the ON state current. The vacuum-deposited TPA-NI-DCN device fabricated as an active memory layer was demonstrated to exhibit write-once-read-many (WORM) switching characteristics of organic nonvolatile memory due to the strong polarity of the TPA-NI-DCN moiety. [ABSTRACT FROM AUTHOR]

Four novel conjugated polymers ( P1-4) with 9,10-disubstituted phenanthrene (PhA) as the donor unit and 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit are synthesized and characterized. These polymers are of medium bandgaps (2.0 eV), low-lying HOMO energy levels (below −5.3 eV), and high hole mobilities (in the range of 3.6 × 10−3 to 0.02 cm2 V−1 s−1). Bulk heterojunction (BHJ) polymer solar cells (PSCs) with P1-4:PC71BM blends as the active layer and an alcohol-soluble fullerene derivative (FN-C60) as the interfacial layer between the active layer and cathode give the best power conversion efficiency (PCE) of 4.24%, indicating that 9,10-disubstituted PhA are potential donor materials for high-efficiency BHJ PSCs. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, and photophysical and photovoltaic properties of two anthracene-containing wide-band-gap donor and acceptor (D-A) alternating conjugated polymers ( P1 and P2) are described. These two polymers absorb in the range of 300-600 nm with a band gap of about 2.12 eV. Polymer solar cells with P1:PC71BM as the active layer demonstrate a power conversion efficiency (PCE) of 2.23% with a high Voc of 0.96 V, a Jsc of 4.4 mA cm−2, and a comparable fill factor (FF) of 0.53 under simulated solar illumination of AM 1.5 G (100 mW cm−2). In addition, P2:PC71BM blend-based solar cells exhibit a PCE of 1.42% with a comparable Voc of 0.89 V, a Jsc of 3.0 mA cm−2, and an FF of 0.53. [ABSTRACT FROM AUTHOR]

Four ethynylene-containing donor-acceptor alternating conjugated polymers P1- P4 with 2,5-bis(dodecyloxy) substituted phenylene or carbazole as the donor unit and benzothiadiazole (BTZ) as the acceptor unit were synthesized and used as donor polymers in bulk heterojunction polymer solar cells. The optical, electrochemical, and photovoltaic properties of these four polymers with the ethylene unit located at different positions of the polymer chains were systematically investigated. Our results demonstrated that absorption spectra and the HOMO and LUMO energy levels of polymers could be tuned by varying the position of the ethynylene unit in the polymer chains. Photovoltaic devices based on polymer/PC71BM blend films spin coated from chloroform and dichlorobenzene solutions were investigated. For all four polymers, open circuit voltages ( Voc) higher than 0.8 V were obtained. P4, with ethynylene unit between BTZ and thiophene, shows the best performance among these four polymers, with a Voc of 0.94 V, a Jsc of 4.2 mA/cm2, an FF of 0.40, and a PCE of 1.6%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

Polymethacrylate with semiconducting side chains ( P1), synthesized by free radical polymerization, was used as a donor material for polymer solar cells. P1 is of high molecular weight ( Mn = 82 kg mol−1), good thermal stability, narrow band gap (1.87 eV), and low-lying HOMO energy level (−5.24 eV). P1 possesses not only the good film-forming ability of polymers but also the high purity of small organic molecules. Power conversion efficiencies (PCEs) of 0.63% and 1.22% have been obtained for solar cells with M1:PC71BM and P1:PC71BM as the active layers, respectively. With PC61BM as the acceptor, PCEs of M1 and P1 based devices decrease to 0.61% and 0.76%, respectively. To the best of our knowledge, this is the first report that free radical polymerization can be used to prepare polymer donors for photovoltaic applications. [ABSTRACT FROM AUTHOR]

Linear and hyperbranched ladder polymers are facilely synthesized by a Pd0-catalyzed Suzuki polycondensation and Friedel-Crafts alkylation. The polymers show blue light emission with typical features of ladder polymers, such as well-resolved absorption and emission spectra, and small Stokes shifts. The polymers contain fewer structural defects and they exhibit good optical and thermal stability. No spectral change is observed after the films of ladder polymers are heated at 110 °C in air for 24 h. [ABSTRACT FROM AUTHOR]

Silole-containing conjugated polymers ( P1 and P2) carrying methyl and octyl substituents, respectively, on the silicon atom were synthesized by Suzuki polycondensation. They show strong absorption in the region of 300-700 nm with a band gap of about 1.9 eV. The two silole-containing conjugated polymers were used to fabricate polymer solar cells by blending with PC61BM and PC71BM as the active layer. The best performance of photovoltaic devices based on P1/PC71BM active layer exhibited power conversion efficiency (PCE) of 2.72%, whereas that of the photovoltaic cells fabricated with P2/PC71BM exhibited PCE of 5.08%. 1,8-Diiodooctane was used as an additive to adjust the morphology of the active layer during the device optimization. PCE of devices based on P2/PC71BM was further improved to 6.05% when a TiO x layer was used as a hole-blocking layer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 [ABSTRACT FROM AUTHOR]