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...
On the premise of strongly crystalline materials involved, it is a challenge to control the phase separation of bulk-heterojunction donor/acceptor active layer to fabricate high-performance polymer solar cells (PSCs). Herein, we develop a molecular design strategy of the third component to synthesize three guest materials (namely BTPT, BTP-Th, and BTP-2Th) to address this issue. We investigate and reveal the effect of crystallinity and miscibility of the third component in controlling the phase separation of Y6-derivatives-based blend film. As a result, a remarkable power-conversion efficiency of 18.53 % is obtained in the ternary PSC based on PTQ10 : m-BTP-PhC6 with BTP-Th as the third component, which is a significant improvement with regard to the efficiency of 17.22 % for the control binary device. Our study offers a molecular design strategy to develop a third component for building ternary PSCs in terms of crystallinity and miscibility regulation.
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