Highly Stable Light Emitting Diodes via Potassium Passivation
Zahra Andaji-Garmaroudi a, Mojtaba Abdi-Jalebi a, Stuart Macpherson a, Alan Bowman a, Richard H. Friend a, Samuel D. Stranks a
a Cavendish Laboratory, Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Roma, Italy, 2019 May 12th - 15th
Organizers: Prashant Kamat, Filippo De Angelis and Aldo Di Carlo
Poster, Zahra Andaji-Garmaroudi, 186
Publication date: 11th February 2019


Mixed-halide lead perovskites have attracted intense attention in the field of photovoltaics and other optoelectronic applications over the past few years. The remarkable properties of this material including high photoluminescence quantum yields (PLQYs) and easy bandgap tunability opens up applications for perovskites as coloured emitters and lasers; high emission yields are also a prerequisite for excellent solar cells. Recently, substantial enhancements have been achieved in the external quantum efficiencies of perovskite light-emitting diodes (PLEDs). However, these devices still have limitations associated with their bandgap stability, lifetime, and reproducibility. Here, we report a significant enhancement in the electroluminescence quantum efficiency, and operational lifetime in PLEDs by adding potassium additives to the emitting triple-cation perovskite layer. We also demonstrate the inhibition of bandgap instability and photoinduced ion-migration in passivated perovskite devices. Transient photoluminescence measurements show the reduction in the fast non-radiative decay with passivation when interfaced with LED device contacts. From STEM–EDX elemental analyses, we observe that potassium passivated LEDs are more chemically stable under continuous operation due to reduced ionic migration within and between layers of the device stack. These results are promising for pushing LEDs and solar cells towards their radiative limits and necessary operational stability requirements for commercialisation.




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