Highly efficient air-stable/hysteresis-free flexible inverted-type planar perovskite and organic solar cells employing a small molecular organic hole transporting material

Saripally Sudhaker Reddy, Sungmin Shin, Um Kanta Aryal, Ryosuke Nishikubo, Akinori Saeki, Myungkwan Song, Sung-Ho Jin

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39 Citations (Scopus)


To acknowledge exceptionally productive flexible perovskite solar cells, low-temperature-processable efficient organic hole transporting materials are very significant for the emerging photovoltaic research. A new organic small molecular hole transporting material (N-(4-(9H-carbazol-9-yl)phenyl)-7-(4-(bis(4-methoxyphenyl)amino)phenyl)-N-(7-(4-(bis(4-methoxyphenyl)amino)phenyl)-9,9-dioctyl-9H-fluoren-2-yl)-9,9-dioctyl-9H-fluoren-2-amine (CzPAF-TPA)) has been rationally designed and synthesized for both highly efficient solution-processed flexible and rigid inverted-type planar heterojunction perovskite solar cells (i-PSCs) and flexible and rigid bulk heterojunction inverted organic solar cells (BHJ IOSCs). The dopant-free CzPAF-TPA-based device displayed significantly improved device performance in solution-processed flexible i-PSCs and flexible BHJ IOSCs with power conversion efficiencies (PCEs) of 12.46% and 7.52%, respectively, with negligible hysteresis, which is superior to that of standard HTM. Furthermore, the high PCE was recorded on rigid ITO substrate in dopant-free i-PSCs (PCE ~ 15.71%) and BHJ IOSCs (PCE ~ 8.74%). Notably, the promising technique of flash-photolysis time-resolved microwave conductivity was also well correlated with the obtained results. In addition to their high device performance in flexible as well as rigid i-PSCs and flexible BHJ IOSCs, they also showed long-term stability over 500 h and 30 days with minimal loss of initial performance.

Original languageEnglish
Pages (from-to)10-17
Number of pages8
JournalNano Energy
Publication statusPublished - Nov 2017
Externally publishedYes


  • Bulk heterojunction organic solar cells
  • Flexible/rigid inverted-type perovskite solar cells
  • Hysteresis-free
  • Small molecular organic hole transporting material
  • Stability
  • Time-resolved microwave conductivity

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