Planar Starburst Hole-Transporting Materials for Highly Efficient Perovskite Solar Cells
Xing-Juan Ma a,b, Xiang-Dong Zhu a, Kai-Li Wang a, Femi Igbari a, Yi Yuan a, Yue Zhang a,b, Chun-Hong Gao b, Zuo-Quan Jiang a,*, Zhao-Kui Wang a,*, and Liang-Sheng Liao a
aInstitute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, PR China
bSchool of Physical Science and Technology, Southwest University, 400715, Chongqing, China
There is a requirement to develop more effective hole-transporting materials (HTMs) than commonly used 2,2’,7,7’-tetrakis(N,N-di-p-methoxyphenylamine)-9,9’-spirobifluorene (Spiro-OMeTAD) to fabricate highly efficient and stable perovskite solar cells. Herein, we reported a new HTM of N2,N2,N5,N5,N11,N11-hexakis(4-methoxyphenyl)indolo[3,2,1-jk]carbazole-2,5,11-triamine (DCZ-OMeTAD) by employing indolo[3,2,1-jk]carbazole (DCZ) as a central building block. In addition, another DCZ-based HTM named as 4,4',4''-(indolo[3,2,1-jk]carbazole-2,5,11-triyl)tris(N,N-bis(4-methoxyphenyl)aniline) (DCZ-OMeTPA) with different arylamines as the electron-rich branch was also synthesized for comparison. CH3NH3PbI3 and (NH2CH=NH2PbI3)1x(CH3NH3PbI3)x based perovskite solar cells (PSCs) by utilizing the low-cost DCZ-OMeTAD as HTM exhibited the power conversion efficiency (PCE) of 19.81% and 21.66%, respectively, which were significantly higher than those of Spiro-OMeTAD based devices (18.06% and 20.08%). Unfortunately, DCZ-OMeTPA based PSCs presented unsatisfied device performance compared with Spiro-OMeTAD based devices. We ascribe it to the inferior charge-extraction capability and poor hole mobility of DCZ-OMeTPA. What’s more, DCZOMeTAD based device also delivered the best cell stability among three HTMs based PSCs, indicating that the newly designed concept by replacing spirobifluorene with DCZ has good potential for developing effective HTMs for high-performance PSCs.