Light-emitting element

US8853680B2 · kind B2 · utility

Assignee

• Semiconductor Energy Laboratory Co., Ltd. · JP

Inventors

• Shunpei Yamazaki · Setagaya, JP
• Satoshi Seo · Yokohama, JP
• Satoko Shitagaki · Yokohama, JP
• Nobuharu Ohsawa · Yokohama, JP
• Hideko Inoue · Yokohama, JP
• Hiroshi Kadoma · Yokohama, JP
• Harue Osaka · Atsugi, JP

Key dates

• Filing date: Mar 26, 2012
• Grant date: Oct 7, 2014
• Expiry date: Jun 5, 2032

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10K2101/90

Abstract

A light-emitting element having extremely high efficiency of approximately 25% is provided. The light-emitting element includes a light-emitting layer which contains a phosphorescent guest, an n-type host, and a p-type host, where the light-emitting layer is interposed between an n-type layer including the n-type host and a p-type layer including the p-type host, and where the n-type host and the p-type host are able to form an exciplex in the light-emitting layer. The light-emitting element exhibits an extremely high emission efficiency (power efficiency of 74.3 lm/W, external quantum efficiency of 24.5%, energy efficiency of 19.3%) at a low driving voltage (2.6 V) at which luminance of 1200 cd/m2 is attainable.