Metal halide perovskites have emerged as a new class of solution processable semiconducting materials with applications in a variety of optoelectronic devices, from photovoltaic, to photodetectors, lasers and light emitting diodes (LEDs). While electrically driven perovskite LEDs have shown great promise with the device efficiency approaching to those of organic and quantum dot LEDs, a number of challenges, such as long term stability and color tenability, remain to be addressed.
In this talk, I will report our work on developing efficient red emitting perovskite LED with great spectral stability by using PEO/qausi-2D perovskites composites as light emitting layer. Cesium lead iodide perovskites were chosen for the consideration of their good thermal and moisture stability, as compared the organic methylammonium counterparts. By facile one step solution processing followed by low temperature thermal treatment, composite thin films of PEO/quasi-2D perovskites can be prepared to exhibit tunable photoluminescence from red to deep red. The addition of PEO leads to a significantly enhanced thin film photoluminescence quantum efficiency (PLQE) and superior thin film morphology. Electrically driven red emitting LEDs with emission peaked at 680 nm have been fabricated to exhibit high brightness of 1500cd/m2 and external quantum efficiency of 4.7%. More importantly, these red perovskite LEDs show great spectral stability and device performance stability during operation.