Hybrid 2D perovskite and red emitting carbon dot composite for improved stability and efficiency of LEDs

Abstract

Organic–inorganic hybrid lead trihalide perovskites have shown promise consistently in optoelectronic devices such as light-emitting diodes (LEDs), solar cells, photodetectors, sensors, and other optoelectronic devices. Perovskite-based LEDs (PSK-LEDs) have shown enormous potential, mostly due to their lower cost, easy synthesis via solution processibility, and highly tunable light-emitting behavior with higher performance. Despite the recent developments in green and blue PSK-LEDs over the years, there has been less development in the research area of red-emitting PSK-LEDs. Although some developments have led to spectrally, stable red-emitting PSK-LEDs, the stability of those devices still needs to be improved upon further for any practical application. In this work, to the best of our knowledge, for the first time, we used red-emitting 2D PSK as an active light-emitting layer which was further stabilized by red-emitting carbon dots (CDs). The CD-PSK composite films were used as an active layer in red emitting LEDs, and they showed high operational stability, and improved performance compared to the control device with only PSK film as the active layer. The composite device showed improved maximum luminescence (3011 cd m⁻²), charge density (330 mA cm⁻²), operational stability (8 hours), better EQE (10.2%), and low turn-on voltage of 2.6 V compared to the control device with maximum luminescence (1512 cd m⁻²), charge density (134 mA cm⁻²), operational stability (<2 hours), EQE (2.6%) and turn on voltage of 3.2 V. The low-cost hybrid approach using PSK building blocks together with CDs opens a new approach leading to a composite material, which has immense possibilities for tuning the structure further to maximize the performance.