title: Ternary Blend Composed of Two Organic Donors and One Acceptor for Active Layer of High-Performance Organic Solar Cells.
abstract: Ternary blends composed of two donor absorbers with complementary absorptions provide an opportunity to enhance the short-circuit current and thus the power conversion efficiency (PCE) of organic solar cells. In addition to complementary absorption of two donors, ternary blends may exhibit favorable morphology for high-performance solar cells when one chooses properly the donor pair. For this purpose, we develop a ternary blend with two donors (diketopyrrolopyrrole-based polymer (PTDPP2T) and small molecule ((TDPP)2Ph)) and one acceptor (PC71BM). The solar cell made of a ternary blend with 10 wt % (TDPP)2Ph exhibits higher PCE of 7.49% as compared with the solar cells with binary blends, PTDPP2T:PC71BM (6.58%) and (TDPP)2Ph:PC71BM (3.21%). The higher PCE of the ternary blend solar cell is attributed mainly to complementary absorption of two donors. However, a further increase in (TDPP)2Ph content in the ternary blend (>10 wt %) decreases the PCE. The ternary blend with 10 wt % (TDPP)2Ph exhibits well-developed morphology with narrow-sized fibrils while the blend with 15 wt % (TDPP)2Ph shows phase separation with large-sized domains, demonstrating that the phase morphology and compatibility of ternary blend are important factors to achieve a high-performance solar cell made of ternary blends.
authors.affiliation: Department of Materials and Engineering, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea.
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Department of Materials and Engineering, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea.
authors.forename: Yoon Suk
authors.initials: YS
authors.lastname: Choi
authors.affiliation: Pohang Accelerator Laboratory , Pohang, Kyungbuk 790-784, Republic of Korea.
authors.forename: Hyungju
authors.initials: H
authors.lastname: Ahn
authors.affiliation: Department of Materials and Engineering, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea.
authors.forename: Won Ho
authors.initials: WH
authors.lastname: Jo
keywords: absorption property; bulk heterojunction; miscibility; organic solar cells; ternary blends