Mesoscopic fully printable perovskite light-emitting diodes in the near infra-red region†

This study presents, for the first time, a fully printable mesoporous indium tin oxide (ITO) perovskite light-emitting diode (ITO-PeLED). The structure comprises triple-oxide screen-printed mesoporous layers, with the perovskite filling the pores of the inorganic framework. These ITO-PeLEDs emit in the near-infrared region achieving an external quantum efficiency (EQE) of 22.07% and a peak radiance of approximately 1000 W sr⁻¹ m⁻². Additionally, they can function as solar cells, exhibiting over 10% efficiency, where the perovskite serves as both a light harvester and a hole conductor simultaneously. Further analysis reveals that the dominant recombination mechanism in these ITO-PeLEDs is Shockley–Read–Hall recombination in the bulk, while a significant energy mismatch between the layers leads to considerable V_oc loss, impacting device functionality. Impedance spectroscopy was employed to investigate the electroluminescence process across different voltage ranges, revealing a correlation between ion current and electroluminescence and emphasizing the critical role of ion migration in radiative recombination. This phenomenon is supported by the improved performance of ITO-PeLEDs observed during stability measurements conducted over multiple cycles. This work demonstrates efficient and fully printable PeLEDs that are suitable for large-scale production.