Lending Triarylphosphine Oxide to Phenanthroline: a Facile Approach to High‐Performance Organic Small‐Molecule Cathode Interfacial Material for Organic Photovoltaics utilizing Air‐Stable Cathodes |
| |
Authors: | Wan‐Yi Tan Rui Wang Min Li Gang Liu Ping Chen Xin‐Chen Li Shun‐Mian Lu Hugh Lu Zhu Qi‐Ming Peng Xu‐Hui Zhu Wei Chen Wallace C. H. Choy Feng Li Junbiao Peng Yong Cao |
| |
Affiliation: | 1. State Key Laboratory of Luminescent Materials and Devices (SKLLMD) and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology (SCUT), Guangzhou, China;2. Department of Physics, National University of Singapore, 3 Science Drive 2, and Department of Chemistry, National University of Singapore, Singapore;3. State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun, China;4. Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China |
| |
Abstract: | Cathode interfacial material (CIM) is critical to improving the power conversion efficiency (PCE) and long‐term stability of an organic photovoltaic cell that utilizes a high work function cathode. In this contribution, a novel CIM is reported through an effective and yet simple combination of triarylphosphine oxide with a 1,10‐phenanthrolinyl unit. The resulting CIM possesses easy synthesis and purification, a high T g of 116 °C and attractive electron‐transport properties. The characterization of photovoltaic devices involving Ag or Al cathodes shows that this thermally deposited interlayer can considerably improve the PCE, due largely to a simultaneous increase in V oc and FF relative to the reference devices without a CIM. Notably, a PCE of 7.51% is obtained for the CIM/Ag device utilizing the active layer PTB7:PC71BM, which far exceeds that of the reference Ag device and compares well to that of the Ca/Al device. The PCE is further increased to 8.56% for the CIM/Al device (with J sc = 16.81 mA cm?2, V oc = 0.75 V, FF = 0.68). Ultraviolet photoemission spectroscopy studies reveal that this promising CIM can significantly lower the work function of the Ag metal as well as ITO and HOPG, and facilitate electron extraction in OPV devices. |
| |
Keywords: | cathode interfacial materials organic photovoltaics organic small molecules phenanthroline phosphine oxide |
|
|