Rational Ion Migration Management for Long-Term Stable Blue Perovskite Light-Emitting Diodes

金属卤化物钙钛矿具有高导电性、高光致发光量子效率和色纯度，是成本效益高的发光二极管（LED）的理想发射体。虽然钙钛矿LED（PeLED）的红色和绿色发光的EQE最近已经提高到超过25%，接近流行的OLED和QLED的EQE，但是实现高效率的蓝色PeLED仍然是一个巨大的挑战。更重要的是，克服PeLED的工作寿命差（蓝色PeLED约为10小时），这被认为是源于钙钛矿发射体中电场引起的严重离子迁移和界面降解，是PeLED进一步发展和未来在显示器和照明中应用的关键。RAIMM的目标是实现EQE超过20%的纯蓝色PeLED（发射波长为465至475 nm），并在100 cd/m2下显著提高寿命超过1，000小时。我的策略使用了几个强大的特征（例如，原位PL、原位EL成像、PL&EL等）揭示了钙钛矿发光体和PeLED的清晰降解机制。因此，我将引入不同的加工添加剂，以实现高度发射的钙钛矿发射体，并大大抑制离子迁移。有了稳定的钙钛矿发射体，新的器件结构将被设计成稳定界面接触并降低PeLED的开启电压。该策略将使跨越PeLED的电场最小化，并限制离子穿透电荷传输层。最后，我将能够实现高效率的纯蓝色PeLED，寿命超过1,000小时，代表PeLED社区的里程碑。我将与Helio Display Materials合作，展示第一个基于钙钛矿的原型显示器，具有Rec.2020色域。我相信我们的研究结果将大大加快PeLED的进展，并刺激其他钙钛矿光电器件的进一步突破。

Metal halide perovskites, which possess high conductivity, high photoluminescence quantum efficiency and color purity, are ideal emitters for cost-effective light-emitting diodes (LEDs). Although EQEs of perovskite LEDs (PeLEDs) emitting in red and green have been boosted to over 25 % recently, approaching that of prevailing OLED and QLEDs, it is still a great challenge to achieve high efficiency blue PeLEDs. More importantly, overcoming poor operational lifetime of PeLEDs (around 10 hours for blue PeLEDs), which is thought to originate from severe ion migration induced by electric field in perovskite emitters and interfacial degradation, is a key for further development of PeLEDs and future applications in displays and lighting. The objective of RAIMM is achieving pure blue PeLEDs (emitting from 465 to 475 nm) with EQEs exceeding 20 % and significantly improved lifetime over 1,000 hours @100 cd/m2. My strategies are using several powerful characterizations (e.g., in-situ PL, in-situ EL imaging, PL&EL, etc.) to reveal a clear degradation mechanism of perovskite emitters and PeLEDs. Accordingly, I will introduce different processing additives to achieve highly emissive perovskite emitters with much suppressed ion migration. With the stable perovskite emitters, new device structures will be designed to stabilize the interfacial contacts and decrease turn-on voltages of PeLEDs. This strategy will minimize the electrical fields across the PeLEDs and limit ion penetration through charge transporting layers. Finally, I will be able to achieve high efficiency pure blue PeLEDs with lifetime over 1,000 h, representing a milestone in PeLEDs community. I will collaborate with Helio Display Materials to demonstrate the first all perovskite-based prototype display with Rec. 2020 color gamut. I believe our results will dramatically accelerate the progress of PeLEDs and stimulate further breakthroughs in other perovskite optoelectronic devices.