title: Donor-Acceptor Interface Stabilizer Based on Fullerene Derivatives toward Efficient and Thermal Stable Organic Photovoltaics.
abstract: An interface stabilizer based on alkylation-functionalized fullerene derivatives, [6, 6]-Phenyl-C61-butyric acid (3,5-bis(octyloxy)phenyl)methyl ester (PCB-C8oc), was successfully synthesized and applied for the active layer of Organic Photovoltaics (OPVs). The PCB-C8oc can replace part of the phenyl-C61-buty-ric acid methyl ester (PCBM) and be distributed on the interface of poly(3-hexylthiophene) (P3HT) and PCBM to form P3HT/PCBM/PCB-C8oc ternary blends, leading to thermally stable and efficient organic photovoltaics. The octyl groups of PCB-C8oc exhibit intermolecular interaction with the hexyl groups of P3HT, and the fullerene unit of PCB-C8oc are in tight contact with PCBM. The dual functions of PCB-C8oc will inhibit the phase separation between electron donor and acceptor, thereby improving the stability of devices under long-time thermal annealing at high temperature. When doped with 10 wt % PCB-C8oc, the power conversion efficiency (PCE) of the P3HT system decreased from 3.54% to 2.88% after 48 h of thermal treatment at 150 °C, whereas the PCE of the reference device without PCB-C8oc dramatically dropped from 3.53% to 0.73%. When doping 10 or 20 wt % PCB-C8oc, the unannealed P3HT/PCBM/PCB-C8oc device achieved a higher PCE than the P3HT/PCBM device without any annealing following the same fabricating condition. For the PTB7/PCBM-based devices, after adding only 5 wt % PCB-C8oc, the OPVs also exhibited thermally stable morphology and better device performances. All these results demonstrate that the utilization of alkyl interchain interactions is an effective and practical strategy to control morphological evolution.
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , Wuhan, 430074, China.
authors.forename: Junli
authors.identifier: http://orcid.org/0000-0003-1673-962X
authors.initials: J
authors.lastname: Li
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , Wuhan, 430074, China.
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , Wuhan, 430074, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yuan
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , Wuhan, 430074, China.
authors.forename: Jiulin
authors.initials: J
authors.lastname: Shen
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , Wuhan, 430074, China.
authors.forename: Jikang
authors.initials: J
authors.lastname: Liu
authors.affiliation: School of Material Science and Technology, Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology , First Jinji Road, Guilin, Guangxi 541004, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , Wuhan, 430074, China.
authors.forename: Guoli
authors.initials: G
authors.lastname: Tu
keywords: aggregation; alkylation-functionalized; interface stabilizer; morphological evolution; organic photovoltaics; thermal stability