Improved performance of small molecule solar cell by using oblique deposition technique and zinc phthalocyanine cathode buffer layer

Tianjiao Zhao; Gengmin Zhang; Yingjie Xing

doi:10.1039/c8ra01136b

Improved performance of small molecule solar cell by using oblique deposition technique and zinc phthalocyanine cathode buffer layer

RSC Adv. 2018 Mar 19;8(20):10999-11005. doi: 10.1039/c8ra01136b. eCollection 2018 Mar 16.

Authors

Tianjiao Zhao¹, Gengmin Zhang¹, Yingjie Xing¹

Affiliation

¹ Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University Beijing 100871 China xingyj@pku.edu.cn.

Abstract

Short circuit current density (J _sc) and open circuit voltage (V _oc) are two important parameters to evaluate the performance of organic solar cells. How to increase these two parameters without using novel material still remains a challenge. Two small molecules, zinc phthalocyanine (ZnPc) and 3,4,9,10-perylene tetracarboxylic bisbenzimidazole (PTCBI), are used to fabricate ITO/ZnPc/ZnPc:PTCBI/PTCBI/ZnPc/Al photovoltaic device. We find that J _sc and V _oc are enhanced by using oblique deposition technique and ZnPc cathode buffer layer, respectively. Analysis of the active layer reveals phase segregation in obliquely deposited ZnPc:PTCBI bulk heterojunction layer. Field emission measurement is used to probe the band bending and internal field in ZnPc/PTCBI planar heterojunction. The effects of phase segregation and internal field are discussed. This work shows that careful assembly of donor and acceptor material is beneficial to small molecule photovoltaic device.