Benzotriazole-Based Polymer Acceptor for High-Efficiency All-Polymer Solar Cells with High Photocurrent and Low Voltage Loss

摘要

The power conversion efficiencies (PCEs) of all-polymer solar cells (all-PSCs)have already exceeded 17%. However, the limited absorption range of an allpolymersystem results in significantly reduced short-circuit current density(J_(sc)), which eventually influences the PCE improvement. To broaden the lightabsorption of polymer acceptors, herein, benzotriazole is introduced in thecore unit of small molecule acceptors and thus two narrow-bandgap polymeracceptors named PTz-BO and PTz-C11 featuring the same molecular backboneand different side-chain length are synthesized. Compared with PTz-C11,the PTz-BO based-all PSCs deliver a slightly reduced J_(sc), a large open-circuitvoltage (V_(oc)) and a low voltage loss below 0.50 V. Moreover, ternary all-PSCsare constructed by introducing PTz-C11 as a guest component. Benefitingfrom the reduced recombination, improved exciton generation and dissociation,and balanced charge transport, a high efficiency of 16.58% is obtainedfor the ternary all-PSCs, with a high J_(sc) over 25 mA cm~(?2) without sacrificingthe V_(oc). Such result represents the highest efficiency reported for benzotriazole-based all-PSCs in the literature thus far. This work demonstrates thegreat potential of benzotriazole for the synthesis of efficient narrow-bandgappolymer acceptors.