The adequate donor/acceptor interface and bicontinuous interpenetrating networks in the BHJ blend facilitates efficient exciton dissociation and charge transport for collection at the electrodes. [5][6][7] In this regard, uniformly phase-separated nanomorphology at the 10-20 nm length scale which formed by the spontaneous phase separation of the donor and acceptor materials has a profound impact on the performance of OSCs. The BHJ bicontinuous interpenetrating network in active layer is formed by the respective self-aggregation of donor and acceptor materials during the film formation process. Nevertheless, due to the different solubility and miscibility of donor and acceptor in processing solvent, casting BHJ blend from a single solvent generally results in an undesirable morphology for efficient OSCs. Therefore, developing morphology control methods to manipulate the morphology of blend film toward advantageous phase separation is critical for fabricating state-of-the-art OSCs. [8][9][10] Incorporation of appropriate solvent as an additive in primary host solvent is one of the most effective and simple approaches to control the aggregation of donor/acceptor materials during the film formation. [11][12][13] The critical operating principles of the solvent additives on controlling the morphology are the selective solubility of solvent additive to either donor or acceptor material and the less volatile with higher boiling points than host solvents. During the past decades in the studies of the OSCs with fullerene derivatives as the dominant acceptors, various kinds of solvents have been developed as additives to optimize the morphology of the fullerene-based blend film because of the characteristic discrepancies between the fullerene derivative acceptors and the π-conjugated p-type organic semiconductor donors. [12] Currently, nonfullerene n-type organic semiconductors with acceptor-donor-acceptor (A-D-A) [14][15][16] or A-DA′D-A [17] molecular backbones have replaced fullerene acceptors as emerging acceptors that significantly drive the development of highly efficient OSCs. Unlike the isotropic cage-like structure of fullerene derivatives, the anisotropic conjugated structures of the nonfullerene acceptors, which are similar to p-type organic semiconductors, bring more complexity and challenge on manipulating their Controlling the self-assembling of organic semiconductors to form welldeveloped nanoscale phase separation in the bulk-heterojunction active layer is critical yet challenging for building high-performance organic solar cells (OSCs). Particularly, the similar anisotropic conjugated structures between nonfullerene acceptors and p-type organic semiconductor donors raise more complexity on manipulating their aggregation toward appropriate phase separation. Herein, a new approach to tune the morphology of photoactive layer is developed by utilizing the synergistic effect of dithieno[3,2-b:2′,3′-d]thiophene (DTT) and 1-chloronaphthalene (CN). The volatilizable solid additive DTT with high crystallinity can r...

Polyhedral oligomeric silsesquioxanes (POSSs) were adsorbed on methylaluminoxane-activated silica for the immobilization of fluorinated bis(phenoxyimine)Ti complexes (FI catalyst). These POSSs have been characterized as horizontal spacers isolating the active sites and hindering the chain overlap in polymerization. The heterogeneous catalyst exhibits considerable activity in the synthesis of weakly entangled polyethylene.

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The use of a ternary active layer offers a promising approach to enhance the power conversion efficiency (PCE) of polymer solar cells (PSCs) via simply incorporating a third component. Here, a ternary PSC with improved efficiency and stability facilitated by a new small molecule IBC‐F is demonstrated. Even though the PBDB‐T:IBC‐F‐based device gives an extremely low PCE of only 0.21%, a remarkable PCE of 15.06% can be realized in the ternary device based on PBDB‐T:IE4F‐S:IBC‐F with 20% IBC‐F, which is ≈10% greater than that (PCE = 13.70%) of the control binary device based on PBDB‐T:IE4F‐S. The improvement in the device performance of the ternary PSC is mainly attributed to the enhancement of fill factor, which is due to the improved charge dissociation and extraction, suppressed bimolecular and trap‐assisted recombination, longer charge‐carrier lifetime, and enhanced intermolecular interactions for preferential face‐on orientation. Additionally, the ternary device with 20% IBC‐F shows better thermal and photoinduced stability over the control binary device. This work provides a new angle to develop the third components for building ternary PSCs with enhanced photovoltaic performance and stability for practical applications.

Currently, morphology optimization methods for the fused‐ring nonfullerene acceptor‐based polymer solar cells (PSCs) empirically follow the treatments originally developed in fullerene‐based systems, being unable to meet the diverse molecular structures and strong crystallinity of the nonfullerene acceptors. Herein, a new and universal morphology controlling method is developed by applying volatilizable anthracene as solid additive. The strong crystallinity of anthracene offers the possibility to restrict the over aggregation of fused‐ring nonfullerene acceptor in the process of film formation. During the kinetic process of anthracene removal in the blend under thermal annealing, donor can imbed into the remaining space of anthracene in the acceptor matrix to form well‐developed nanoscale phase separation with bi‐continuous interpenetrating networks. Consequently, the treatment of anthracene additive enables the power conversion efficiency (PCE) of PM6:Y6‐based devices to 17.02%, which is a significant improvement with regard to the PCE of 15.60% for the reference device using conventional treatments. Moreover, this morphology controlling method exhibits general application in various active layer systems to achieve better photovoltaic performance. Particularly, a remarkable PCE of 17.51% is achieved in the ternary PTQ10:Y6:PC71BM‐based PSCs processed by anthracene additive. The morphology optimization strategy established in this work can offer unprecedented opportunities to build state‐of‐the‐art PSCs.

A dialkylthio-substituted conjugated polymer is designed and synthesized as a donor material for high-performance polymer solar cells with long-term stability.

We design and synthesize a new main-chaintwisted fused-ring narrow band gap n-type organic semiconductor acceptor (namely, IE4F-S) with a terminal group on the 4-position of 3-alkylthio-substituted thiophene. The acceptor IE4F-S shows zero ionization potential (IP) offset (ΔIP) with a wide band gap polymer donor PTQ10. Notably, the polymer solar cell (PSC) device operating at such a negligible ΔIP can still yield an outstanding power conversion efficiency (PCE) of 12.20%, with a high open-circuit voltage (V oc ) of 0.996 V and a remarkably low energy loss of 0.47 eV. The energy loss of 0.47 eV should be the lowest value for the reported PSCs with PCE of over 12%. In addition, by using PBDB-T as a donor to blend with IE4F-S, the PSC device also demonstrates a promising PCE of 13.72%, which is one of the top efficiencies for PBDB-T-based devices. The results demonstrate that appropriate modulation of the main-chain planarity is an effective approach to construct high-performance fused-ring-based acceptors for PSCs.

Fe(acac) 3 /2,6-bis [1-(2-isopropylanilinoethyl)] pyridine catalyst was immobilized on MCM-41 zeolite to synthesize ultrahigh molecular weight polyethylene (UHMWPE) with a weakly entangled state. Microstructure, morphology, crystallization, and rheological properties of the nascent polyethylene were investigated by gel permeation chromatography, scanning electron microscope, differential scanning calorimetry, and rheometer, respectively. The polymer showed broad molecular weight distribution. We found that the synthesized UHMWPE had a weakly entangled state. The evolution of the weakly entangled state of the polymer was studied; however, it was found that the polymer synthesized in the initial stage of polymerization could be more entangled. Thus, poly[styrene-co-(acrylic acid)] (PSA) was coated on the surface of Cat-Fe/M to control the diffusion rate of ethylene, especially during the initial stage of polymerization. The decay rate of catalyst activity was decreased. The polymer synthesized at this stage then became more weakly entangled. The mechanism for achieving the weakly entangled state during polymerization was further discussed.