Publications associated with Advanced Functional Materials and Devices Group

Improved organic p-i-n type solar cells with n-doped fluorinated hexaazatrinaphthylene derivatives HATNA-F<inf>6</inf> and HATNA-F<inf>12</inf> as transparent electron transport material

Journal of Applied Physics 115 (2014)

F Selzer, C Falkenberg, M Hamburger, M Baumgarten, K Müllen, K Leo, M Riede

We study new electron transport materials (ETM) to replace the reference material C 60 in p-i-n type organic solar cells. A comprehensive material characterization is performed on two fluorinated hexaazatrinaphthylene derivatives, HATNA-F 6 and HATNA-F 12 , to identify the most promising material for the application in devices. We find that both HATNA derivatives are equally able to substitute C 60 as ETM as they exhibit large optical energy gaps, low surface roughness, and sufficiently high electron mobilities. Furthermore, large electron conductivities of 3.5×10-5 S/cm and 2.0×10-4 S/cm are achieved by n-doping with 4 wt. % W 2 (hpp) 4 . HOMO levels of (7.72 ± 0.05) eV and (7.73 ± 0.05) eV are measured by ultraviolet photoelectron spectroscopy and subsequently used for estimating LUMO values of (4.2 ± 0.8) eV and (4.3 ± 0.8) eV. Both fluorinated HATNA derivatives are successfully applied in p-i-n type solar cells. Compared to identical reference devices comprising the standard material C 60 , the power conversion efficiency (PCE) can be increased from 2.1 % to 2.4 % by using the new fluorinated HATNA derivatives. © 2014 AIP Publishing LLC.

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