Proceedings of September Meeting 2016 (NFM16)
Publication date: 14th June 2016
Hybrid Halide Perovskite are probably the current hottest materials for photovoltaics. Certified photoconversion efficiencies as high as 21% has been reported. In order to obtain efficiencies as the ones reported for PSCs it is needed a low non-radiative recombination. Consequently Hybrid halide perovskite present an outstanding properties for light emission. In addition, Perovskite Solar Cells (PSCs) can be prepared from solution methods at low temperature, and consequently they can be fabricated without large and expensive facilities, and can be easily combined with other materials. The interaction among materials of different nature can produce interesting synergies that might be beneficial, not simply by improving a feature, but also giving rise to new properties or phenomena that do not exist for the single materials. We have studied the interaction between hybrid lead halide perovskite (CH3NH3PbI3) and quantum dots (core/shell PbS/CdS).1 Interaction between QDs and perovskite has enormous potentialities.1-3 We report for the first time the observation of exciplex state electroluminescence from the combination of both materials. Single layers of perovskite (PS) and quantum dots (QDs) have been produced by solution processing methods and their emission properties are compared to the case of bilayer samples in both configurations PS/QD and QD/PS. In addition layers with QDs embedded in the perovskite matrix have been also prepared by a new one step method. Exciplex emission at lower energies than the band gap of both PS and QD has been detected. The exciplex emission wavelength of this mixed system can be simply tuned by controlling the QD size. Light Emitting Devices (LEDs) have been fabricated using those configurations, which provide light emission with considerably low turn-on potential. Interestingly the ʹcolorʹ of the LED can also be tuned by controlling the applied bias. The presence of the exciplex state PS and QDs opens up a broad range of possibilities with important implications in tunable LEDs but also in the preparation of intermediate band gap photovoltaic devices with the potentiality of surpassing the Shockley-Queisser (SQ) limit.
1. Sanchez, R. S.; de la Fuente, M. S.; Suarez, I.; Muñoz-Matutano, G.; Martinez-Pastor, J. P.; Mora-Sero, I. Science Advances 2016, 2 (1), e1501104.
2. Yang, Z.; Janmohamed, A.; Lan, X.; García de Arquer, F. P.; Voznyy, O.; Yassitepe, E.; Kim, G.-H.; Ning, Z.; Gong, X.; Comin, R.; Sargent, E. H. Nano Lett. 2015, 15 (11), 7539-7543.
3. Ning, Z.; Gong, X.; Comin, R.; Walters, G.; Fan, F.; Voznyy, O.; Yassitepe, E.; Buin, A.; Hoogland, S.; Sargent, E. H. Nature 2015, 523 (7560), 324-328.