Novel integrated reference-counter electrode for electrochemical measurements of HOMO and LUMO levels in small-molecule thin-film semiconductors for OLEDs

IF 2.7 4区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Organic Electronics Pub Date : 2024-10-28 DOI:10.1016/j.orgel.2024.107152

Sevki C. Cevher, Kurt P. Pernstich

{"title":"Novel integrated reference-counter electrode for electrochemical measurements of HOMO and LUMO levels in small-molecule thin-film semiconductors for OLEDs","authors":"Sevki C. Cevher, Kurt P. Pernstich","doi":"10.1016/j.orgel.2024.107152","DOIUrl":null,"url":null,"abstract":"<div><div>Organic light-emitting diodes (OLEDs) are a prominent display technology, yet the accurate characterization of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels in their constituent materials remains challenging. This study introduces a novel integrated reference-counter electrode (IRCE) assembly, leveraging a gel polymer electrolyte with an embedded silver quasi-reference electrode, facilitating the electrochemical measurement of HOMO and LUMO levels in small molecular thin-film semiconductors. Calibration of the IRCE against ferrocene enables the establishment of an absolute energy scale. Comparative stability tests against a standard Ag/AgNO<sub>3</sub> reference electrode confirm the IRCE's reliability. Electrochemical characterization using cyclic voltammetry was performed on prototypical OLED materials, including NPB, TCTA, PO-T2T neat films, and an NPB:PO-T2T exciplex film. While NPB and PO-T2T exhibited stable voltammograms, TCTA showed signs of electropolymerization. Additionally, the HOMO level of the NPB:PO-T2T exciplex was slightly shifted compared to that of NPB, suggesting interactions within the exciplex. The results demonstrated the IRCE's capability to accurately determine frontier energy levels in thin films, paving the way for better device modeling and a better understanding of underlying electronic processes in organic semiconductors.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"136 ","pages":"Article 107152"},"PeriodicalIF":2.7000,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Organic Electronics","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1566119924001630","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}

引用次数: 0

Abstract

Organic light-emitting diodes (OLEDs) are a prominent display technology, yet the accurate characterization of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels in their constituent materials remains challenging. This study introduces a novel integrated reference-counter electrode (IRCE) assembly, leveraging a gel polymer electrolyte with an embedded silver quasi-reference electrode, facilitating the electrochemical measurement of HOMO and LUMO levels in small molecular thin-film semiconductors. Calibration of the IRCE against ferrocene enables the establishment of an absolute energy scale. Comparative stability tests against a standard Ag/AgNO₃ reference electrode confirm the IRCE's reliability. Electrochemical characterization using cyclic voltammetry was performed on prototypical OLED materials, including NPB, TCTA, PO-T2T neat films, and an NPB:PO-T2T exciplex film. While NPB and PO-T2T exhibited stable voltammograms, TCTA showed signs of electropolymerization. Additionally, the HOMO level of the NPB:PO-T2T exciplex was slightly shifted compared to that of NPB, suggesting interactions within the exciplex. The results demonstrated the IRCE's capability to accurately determine frontier energy levels in thin films, paving the way for better device modeling and a better understanding of underlying electronic processes in organic semiconductors.

Abstract Image

查看原文本刊更多论文

用于 OLED 小分子薄膜半导体中 HOMO 和 LUMO 电平电化学测量的新型集成参比对电极

有机发光二极管（OLED）是一种重要的显示技术，但要准确表征其组成材料中的最高占位分子轨道（HOMO）和最低未占位分子轨道（LUMO）电平仍然具有挑战性。本研究介绍了一种新型集成参比电极（ICE）组件，它利用凝胶聚合物电解质和嵌入式银准参比电极，促进了小分子薄膜半导体中 HOMO 和 LUMO 水平的电化学测量。根据二茂铁对 IRCE 进行校准，可以建立绝对能量标度。与标准银/AgNO3 参比电极的稳定性比较测试证实了 IRCE 的可靠性。使用循环伏安法对原型 OLED 材料进行了电化学表征，包括 NPB、TCTA、PO-T2T 纯薄膜和 NPB:PO-T2T 复合物薄膜。NPB 和 PO-T2T 显示出稳定的伏安图，而 TCTA 则显示出电聚合的迹象。此外，与 NPB 相比，NPB:PO-T2T 复合物的 HOMO 水平略有偏移，这表明复合物内部存在相互作用。结果表明，IRCE 能够准确测定薄膜的前沿能级，为更好地进行器件建模和更好地了解有机半导体的基本电子过程铺平了道路。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Organic Electronics 工程技术-材料科学：综合

CiteScore

6.60

自引率

6.20%

发文量

238

审稿时长

44 days

期刊介绍： Organic Electronics is a journal whose primary interdisciplinary focus is on materials and phenomena related to organic devices such as light emitting diodes, thin film transistors, photovoltaic cells, sensors, memories, etc. Papers suitable for publication in this journal cover such topics as photoconductive and electronic properties of organic materials, thin film structures and characterization in the context of organic devices, charge and exciton transport, organic electronic and optoelectronic devices.