State-of-the-art external quantum efficiencies (EQEs) have exceeded 20% for near-infrared, red, and green perovskite light-emitting diodes (PeLEDs) so far. Nevertheless, the cutting-edge blue counterparts demonstrate an inferior device performance, which impedes the commercialization and industrialization of PeLEDs in ultrahigh-definition displays. As the most popular hole transport layer, poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) bears the acidic and hygroscopic drawbacks, which deteriorates the device efficiency and long-term stability of blue PeLEDs. In this work, the basic amino acids with zwitterionic characteristics are proposed to modulate the pH of PEDOT:PSS, which are arginine, lysine, and histidine. It is found that they play a triple function to the blue perovskite films: modulating the acidity of PEDOT:PSS, controlling the crystalline process, and passivating the defects at the PEDOT:PSS/perovskite interface. As a result, the utilization of neutral PEDOT:PSS leads to a significant enhancement in stability and photoluminescence quantum yield. Eventually, the pure-blue PeLEDs achieve a record EQE of 5.6% with the emission peak at 467 nm. This research proves that the interfacial engineering of hole transport layers is a reliable strategy to enhance the device efficiency and operation stability of blue PeLEDs.

中文翻译：

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碱性氨基酸调制的中性 pH PEDOT:PSS 用于稳定的蓝色钙钛矿发光二极管

迄今为止，近红外、红色和绿色钙钛矿发光二极管 (PeLED) 的最先进的外部量子效率 (EQE) 已超过 20%。然而，尖端的蓝色对应物表现出较差的器件性能，这阻碍了 PeLED 在超高清显示器中的商业化和产业化。作为最流行的空穴传输层，聚（3,4-乙烯二氧噻吩）：聚苯乙烯磺酸盐（PEDOT：PSS）具有酸性和吸湿性的缺点，这会降低蓝色PeLED的器件效率和长期稳定性。在这项工作中，提出了具有两性离子特性的碱性氨基酸来调节 PEDOT:PSS 的 pH 值，它们是精氨酸、赖氨酸和组氨酸。发现它们对蓝色钙钛矿薄膜起到三重作用：调节 PEDOT:PSS 的酸度，控制结晶过程，并钝化 PEDOT:PSS/钙钛矿界面处的缺陷。因此，中性 PEDOT:PSS 的使用导致稳定性和光致发光量子产率的显着提高。最终，纯蓝色 PeLED 的 EQE 达到创纪录的 5.6%，发射峰位于 467 nm。该研究证明空穴传输层的界面工程是提高蓝色PeLED器件效率和运行稳定性的可靠策略。