Abstract
Solution-processable perovskites show highly emissive and good charge transport, making them attractive for low-cost light-emitting diodes (LEDs) with high energy conversion efficiencies. Despite recent advances in device efficiency, the stability of perovskite LEDs is still a major obstacle. Here, we demonstrate stable and bright perovskite LEDs with high energy conversion efficiencies by optimizing formamidinium lead iodide films. Our LEDs show an energy conversion efficiency of 10.7%, and an external quantum efficiency of 14.2% without outcoupling enhancement through controlling the concentration of the precursor solutions. The device shows low efficiency droop, i.e. 8.3% energy conversion efficiency and 14.0% external quantum efficiency at a current density of 300 mA cm−2, making the device more efficient than state-of-the-art organic and quantum-dot LEDs at high current densities. Furthermore, the half-lifetime of device with benzylamine treatment is 23.7 hr under a current density of 100 mA cm−2, comparable to the lifetime of near-infrared organic LEDs.
Highlights
Solution-processable perovskites show highly emissive and good charge transport, making them attractive for low-cost light-emitting diodes (LEDs) with high energy conversion efficiencies
The precursor solution consists of a 10 wt.% of formamidinium iodide (FAI) and PbI2 with a molar ratio of 2:1 in N, N-dimethylformamide (DMF)
We believe that the significantly improved stability is due to the high ECE, since low efficiency FAPbI3 perovskite light-emitting diodes (PeLEDs) devices can only have similar lifetime to previous results
Summary
Solution-processable perovskites show highly emissive and good charge transport, making them attractive for low-cost light-emitting diodes (LEDs) with high energy conversion efficiencies. The half-lifetime of device with benzylamine treatment is 23.7 hr under a current density of 100 mA cm−2, comparable to the lifetime of near-infrared organic LEDs. Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, 211816 Nanjing, China. By using around 400 nm perovskite film to improve the coverage, Cho et al has obtained PeLED with an external quantum efficiency (EQE) of 8.3%5 Such a thick perovskite film can reduce charge transport and increase operation voltage of the devices, which leads to low energy conversion efficiencies (ECEs). We demonstrate the fabrication of such perovskite films based on pure FAPbI3 by controlling the concentration of the precursor solutions during spin-coating process
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