Methoxy groups on bifluorenylidene-based hole transporting materials result in highly efficient and stable dopant-free inverted perovskite solar cells. (February 2019)

• Record Type: Journal Article
• Authors: Chen, Yung-Chung; Yen, Jui-Hua; Chung, Chung-Lin; Chen, Chih-Ping
• Is Part Of: Solar energy. Volume 179(2019)
• Page Start: 371
• Page End: 379
• Publication Date: 2019-02
• Subjects: Bifluorenylidene -- Hole-transporting materials -- Hydrophobicity -- Inverted perovskite solar cells -- Methoxy groups; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2019.01.008
• Languages: English
• ISSNs: 0038-092X

Abstract

Graphical abstract: Highlights: Three bifluororenylidene-based compounds (HTM-1-3) have been synthesized. Of the dopant-free inverted PSCs, the HTM-2–based device exhibited the PCE of 12.0%. More hydrophobic properties resulting better device stability. Abstract: Three bifluororenylidene-based compounds featuring different numbers of methoxy groups (none forHTM-1, four forHTM-2, and eight forHTM-3 ) have been synthesized simply and inexpensively and applied as hole transporting materials (HTMs) in inverted perovskite solar cells (PSCs). For comparison, a typical inverted HTM material, PEDOT:PSS, was also applied in a corresponding inverted PSC. The corresponding cell performances were compared with respect to their number of methoxy groups. Of the PSCs containing the bifluororenylidene-based compounds, theHTM-2 –based device exhibited the highest power conversion efficiency (PCE) of 12.0%, with a value of J sc of 19.4 mA cm −2, a value of V oc of 0.94 V, and a fill factor of 65.6%. In addition, the PCE of thisHTM-2 –based device was higher than that (9.9%) of the PEDOT:PSS–based cell under similar testing conditions. The relatively high PCE of theHTM-2 –based cell was due to its suitable energy levels, relatively high hole mobility, and relatively large grains. Furthermore, the HTM series of compounds were also more hydrophobic than PEDOT:PSS and, therefore, they imparted device stability superior to that of the PEDOT:PSS–based cell.