Liu.peng.uppsala

Publication date: 15 March 2017
Source:Journal of Power Sources, Volume 344
Author(s): Peng Liu, Bo Xu, Yong Hua, Ming Cheng, Kerttu Aitola, Kári Sveinbjörnsson, Jinbao Zhang, Gerrit Boschloo, Licheng Sun, Lars Kloo
Two low-cost, easily synthesized π-conjugated molecules have been applied as hole-transport materials (HTMs) for solid state dye-sensitized solar cells (ssDSSCs) and perovskite solar cells (PSCs). For X1-based devices, high power conversion efficiencies (PCEs) of 5.8% and 14.4% in ssDSSCs and PSCs has been demonstrated. For X14-based devices, PCEs were improved to 6.1% and 16.4% in ssDSCs and PSCs, respectively.

Publication date: December 2016
Source:Nano Energy, Volume 30
Author(s): Ming Cheng, Kerttu Aitola, Cheng Chen, Fuguo Zhang, Peng Liu, Kári Sveinbjörnsson, Yong Hua, Lars Kloo, Gerrit Boschloo, Licheng Sun
Perovskite solar cells (PSCs) have attracted significant interest and hole transporting materials (HTMs) play important roles in achieving high efficiency. Here, we report additive free ionic type HTMs that are based on 2-ethylhexyloxy substituted benzodithiophene (BDT) core unit. With the ionization of end-capping pyridine units, the hole mobility and conductivity of molecular materials are greatly improved. Applied in PSCs, ionic molecular material M7-TFSI exhibits the highest efficiency of 17.4% in the absence of additives [lithium bis(trifluoromethanesulfonyl)imide and 4-tert-butylpyridine]. The high efficiency is attributed to a deep highest occupied molecular orbital (HOMO) energy level, high hole mobility and high conductivity of M7-TFSI. Moreover, due to the higher hydrophobicity of M7-TFSI, the corresponding PSCs showed better stability than that of Spiro-OMeTAD based ones. In addition, the strong absorption and suitable energy levels of materials (M6, M7-Br and M7-TFSI) also qualify them as donor materials in organic solar cells (OSCs) and the devices containing M7-TFSI as donor material displayed an efficiency of 6.9%.

Graphical abstract