Quasi-2D perovskite emitters: a boon for efficient blue light-emitting diodes

Abstract

Metal halide perovskites have accomplished excellent progress as forefront materials for near-infrared, red and green perovskite light-emitting-diodes (PeLEDs) with external quantum efficiencies (EQEs) reaching above 20%, promising a bright future for next-generation printable energy-efficient lighting and display technologies. Empathetically, the perovskite blue emitters and corresponding PeLEDs with inherent circumscribed progression, are lagging far behind in performance compared to their other color counterparts, owing to low photoluminescence quantum yields (PLQYs), poor stability and inefficient charge injection. Howsoever, thanks to the layered quasi-2D perovskites (Q2DPe) for exhibiting enhanced PLQYs, color-tunability, improved environmental and operational stability owing to their tunable exciton binding energies arising from the bulky organic cation incorporation. Hence, acknowledging the progressive evolution of blue emitters and the performance of blue PeLEDs from Q2DPe, they are believed to be the best solution so far to address the challenges associated with the blue LEDs and this is indubitably an emerging research area in the present scenario. A comprehensive and profound understanding of compositional engineering to achieve high PLQYs by reducing the defect state density, blocking the ion migration effects in mixed halide systems for spectral stability and promising design strategies to achieve phase purity (desired and concentrated n) for narrow emission is the need of the hour. Therefore, this perspective builds on the envelope of an overview of Q2DPe blue emitters and blue PeLEDs, where we have reinforced our critical views on the evolution of the recent attempts to tune Q2DPe structural, chemical and optical properties. Moreover, this perspective emphasizes on passivation, thin-film morphology, interface engineering and the substantial progress accomplished to date to obtain better performing Q2DPe LEDs. Finally, we have presented a roadmap for further investigations addressing the current challenges and plausible potential prospects in the pursuit of efficient Q2DPe blue emitters and blue LEDs.