Elucidating the role of two-dimensional cations in green perovskite light emitting diodes,

Aurimas Vyšniauskas, Simon Keegan, Kasparas Rakstys, Tobias Seewald, Vytautas Getautis, Lukas Schmidt-Mende, Azhar Fakharuddin

Organic Electronics, Volume 111, 2022, 106655, ISSN 1566-1199

doi.org/10.1016/j.orgel.2022.106655

Perovskite light emitting diodes (PeLEDs) have emerged as promising candidates for applications requiring visible and near-infrared emission.

In this work, the researchers demonstrate the importance of compositional tuning using three different 2D cations namely phenylethylammonium (PEA), its monofluorinated analogue FPEA and a custom-made bulkier cation BPEA containing an extra phenyl ring.

Their results show that the tuning of the ratio between 2D cation and the [PbX6]4- provides a trade-off between electrical transport in the device and the emission properties of the emissive layer.

Generally, a large excess of cations is required to enhance the external quantum efficiency (EQE) of PeLEDs. Among the various cations, FPEA leads to PeLEDs with the highest EQE up to 7.7%, while BPEA resulted in the smallest EQE.

External quantum efficiencies (EQEs), current density-voltage-luminance dependencies, electroluminescence spectra and lifetimes were measured using Fluxim’s Phelos angular luminescence spectrometer. EQE and lifetime measurements were performed at 1 mA current. EQE measurements were performed at a given current density to minimize time for characterisation and degradation of the device. Absorbance of the perovskite films were measured using Agilent Cary 5000 UV-Vis-NIR spectrometer.