Improving performance of Cs-based perovskite light-emitting diodes by dual additives consisting of polar polymer and n-type small molecule

• Published in: Organic electronics Vol. 67; pp. 294 - 301
• Main Authors: Huang, Ming-Yi, Veeramuthu, Loganathan, Kuo, Chi-Ching, Liao, Yi-Chun, Jiang, Dai-Hua, Liang, Fang-Cheng, Yan, Zhen-Li, Borsali, Redouane, Chueh, Chu-Chen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2019; Elsevier
• Subjects: Additives; Chemical Sciences; Engineering Sciences; Light-emitting diodes; Material chemistry; Materials; Perovskite; Polyethylene oxide; Polymers; Small molecule; Perovskite; Additives; Small molecule; Light-emitting diodes; Polyethylene oxide
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2018.12.042

Organic-inorganic halide perovskites were emerging as promising light emitters due to the high photoluminescence quantum efficiency (PLQE), narrow color spectrum, and facile bandgap tunability. However, the morphological issues of this class of materials remain as a bottleneck in generating high-performance light-emitting devices (LED). In this work, we describe a facile and cost-effective method to improve the morphology of an all-inorganic-perovskite emissive layer by using a dual-additive blending strategy. A polar polymer, polyethylene oxide (PEO), and an n-type small molecule, TPBi, are blended with CsPbBr3 to provide synchronous effect in passivizing the surface defects and reducing the exciton quenching, as evidenced by the formation of smaller uniform grains and improved radiative recombination lifetime. Consequently, the optimized CsPbBr3/PEO/TPBi LED reaches maximum luminance, current efficiency, and external quantum efficiency of 6807 cd m−2 (at 6 V), 0.86 cd A−1 (at 5.5 V) and 0.25% (at 5.5 V), far surpassing the performance of the control CsPbBr3 device. On this basis, we further demonstrated a proof-of-concept LED device with touch-responsivity by using a flexible composite electrode. The merit of dual-additive strategy has been clearly manifested and will facilitate the future development of cost-effective solution processable perovskite LEDs. The effectiveness of dual additives on improving the film quality of CsPbBr3 and the performance of its derived LED was manifested by introducing perovskite nanocrystals into a hybrid matrix consisting of polymer (PEO) and small molecule (TPBi). It is revealed that the blended PEO enhances film quality and smoothness while the blended TPBi promotes the electron injection efficiency. This cooperative effect simultaneously improves the device reliability and rectifies the electron and hole injection imbalance, enabling a substantial increase in the luminance and current efficiency of the derived LEDs. [Display omitted] •The effectiveness of dual additives on improving the film quality of CsPbBr3 and the performance of its derived LED.•The morphological issues of materials remain as a bottleneck in generating high-performance LED.•PEO and TPBi are blended with CsPbBr3 to provide synchronous effect in passivizing the surface defects and reducing the exciton quenching.•A proof-of-concept LED device with touch-responsivity by using a flexible composite electrode.