Sonication effect on all-polymer solar cell performance

In this paper, we demonstrated an effect of ultrasonication on the photoactive layer solution of polymer solar cell (PSC). We have fabricated the conventional polymer cells with active layer of poly(3-hexylthiophene) (P3HT) and poly[(9,9-dioctyluorene)-2,7-diyl-alt-(4,7-bis(3-hexylthien-5-yl)-2,1,3-benzothiadiazole)-2′,2″-diyl] (F8TBT). Ultrasonic irradiation was performed on the blend of active layer solution for different time-period. The PSC with ultrasonic irradiation shows degradation in power conversion efficiency (PCE) with respect to the increase in treatment time period. The PSC with just 3 min ultrasonic irradiation shows a 37% decrease in open circuit voltage as compared to the reference device. Also, the PCE of ultrasonically treated (3 min) PSC is reduced to 0.509% from 0.893%. The overall performance degradation attributed to a mechanical rapid movement of molecule overcomes the intermolecular forces in the solution and breaks the polymer chain. The effect of ultrasonic irradiation on blend solution was confirmed by using optical (UV-vis absorption and PL) and morphological study.