Boosting Perovskite Light-Emitting-Diodes Performance via Tailoring Interfacial Contact.

Solution-processed perovskite light emitting diodes (LEDs) have attracted wide attentions in the past several years. However, the overall efficiency and stability of perovskite-based LEDs remains inferior to those of organic or quantum dot LEDs. Non-radiative charge recombination and the unbalanced charge injection are two critical factors that limit the device efficiency and operational stability of perovskite LEDs. Here, we develop a strategy to modify the interface between hole transport layer and the perovskite emissive layer with an amphiphilic conjugated polymer of poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN). We show evidences that PFN improves the quality of perovskite film, which effectively suppresses non-radiative recombination. With further improving charge injection balance rate, a green perovskite LED with a champion current efficiency of 45.2 cd/A, corresponding to an external quantum efficiency (EQE) of 14.4%, is achieved. In addition, the device based on PFN layer exhibits improved operational lifetime. Our work paves a facile way for the development of efficient and stable perovskite LEDs.