Quasi 2D perovskite with PLQY exceeding 80%
Henk J. Bolink a, Michele Sessolo a, Giulia Longo a, Azin Babaei a, Maria-Grazia La-Placa a, Laura Martínez-Sarti a
a Universidad de Valencia - ICMol (Institute of Molecular Science), Catedrático José Beltrán Martinez 2, Paterna, Spain
nanoGe Perovskite Conferences
Proceedings of Perovskite Thin Film Photovoltaics (ABXPV17)
València, Spain, 2017 March 1st - 2nd
Organizers: Henk Bolink and David Cahen
Poster, Maria-Grazia La-Placa, 073
Publication date: 18th December 2016

 

Organic-inorganic (hybrid) perovskites are interesting semiconductor materials for optoelectronics devices. Beside their application in photovoltaics, perovskites are emerging as promising components of light-emitting diodes (LEDs). In electroluminescent devices, a high photoluminescence quantum yield (PLQY) is desirable in order to efficiently convert the injected charges into photons. Unfortunately, the PLQY of 3-dimensional (3D) perovskites such as methylammonium lead bromide (MAPbBr3) strongly depends on excitation intensity, and reaches high values only at high excitation fluence where radiative bimolecular recombination dominates. On the other hand, trap-assisted non-radiative recombination dominates at low excitation, resulting in a low PLQY (< 5%). As a consequence, LEDs need high current densities in order to produce significant light emission, resulting in a low power conversion efficiency. A strategy to enhance the luminescent properties of perovskite films and hence the efficiency of LEDs is the use of so-called quasi-2D structures. Quasi-2D perovskites consist of mixed cation compounds with stoichiometry (RA)2(MA)n-1PbnX3n+1 where n represents a number of 3D perovskite layers between the more bulky organic linkers RA. The addition of the organic linkers impedes the growth of extended 3D crystals, thereby increasing the radiative recombination rate and hence the PLQY. We present a quasi-2D perovskite where the organic linker is butylammonium bromide (BABr), enabling the assembly in very uniform thin films with reduced particle size, low roughness and very high PLQY (>80 %). Thin-films of these materials have been applied in multilayer LEDs, and the use of energetically optimized charge transport layers together with the passivation of the perovskite surface resulted in current efficiency exceeding 3 cd/A.



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