Room-temperature photocurrent measurements in two-dimensional inorganic-organic perovskite devices reveal that excitons strongly contribute to the photocurrents despite possessing binding energies over ten times larger than thermal energies. The p-type (C₆H₉C₂H4NH₃)₂PbI₄ [CHPI] liberates photocarriers at metallic Schottky Al contacts, but incorporating electron and hole transport layers enhances the extracted photo-currents by a hundred-fold.
A further ten-fold gain is found when integrating TiO₂ nanoparticles directly into the perovskite layers, although the 2D excitons semic onducting layers are not significantly disrupted. These results show that strong excitonic materials may be useful as photovoltaic materials despite high exciton binding energies, and suggest mechanisms to better understand photovoltaic properties of the related 3D perovskites.
Ahmad, S., Kanaujia, P. K., Beeson, H. J., Abate, A., Deschler, F., Credgington, D., Steiner, U., et al. (2015). Strong photocurrent from 2D excitons in solution-processed stacked perovskite semiconductor sheets. ACS Applied Materials & Interfaces, 7 (45), 25227-25236.
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Category: Solar & Photovoltaics