Employment of thin perovskite shells and metal halides as surface-passivants for colloidal quantum dots (CQDs) have been important, recent developments in CQD optoelectronics. These have opened the route to single-step deposited high-performing CQD solar cells. These promising architectures employ a QD hole-transporting layer (HTL) whose intrinsically shallow Fermi level (EF) restricts band-bending at maximum power-point during solar cell operation limiting charge collection. Here, we demonstrate a generalized approach to effectively balance band-edge energy levels of the main CQD absorber and charge-transport layer for these high-performance solar cells. Briefly soaking the QD HTL in a solution of the metal-organic p-dopant, molybdenum tris(1-(trifluoroacetyl)-2-(trifluoromethyl)ethane-1,2-dithiolene), effectively deepens its Fermi level, resulting in enhanced band bending at the HTL:absorber junction. This blocks the back-flow of photo-generated electrons, leading to enhanced photocurrent and fill factor compared to undoped devices. We demonstrate 9.0% perovskite-shelled and 9.5% metal-halide-passivated CQD solar cells, both achieving ca. 10% relative enhancements over undoped baselines.
|Original language||English (US)|
|Number of pages||8|
|Journal||ACS Energy Letters|
|State||Published - Aug 8 2017|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors thank Yadong Zhang (Georgia Institute of Technology) for the chemical synthesis of the metal-organic complex, Mo(tfd-COCF3)3, used in this study. F.P.G.A., J. Z. F., G. W., S. H., and E. H. S. thank the Award KUS-11-009-21 from King Abdullah University of Science and Technology (KAUST), the Ontario Research Fund - Research Excellence Program, and the Natural Sciences and Engineering Research Council of Canada (NSERC). M. M. S., S.B., and S. R. M. thank the Office of Naval Research for support through (N00014-14-1-0126). F.P.G.A. acknowledges financial support from the Connaught Fund.