title: Benzophenones as Generic Host Materials for Phosphorescent Organic Light-Emitting Diodes.
abstract: Despite the fact that benzophenone has traditionally served as a prototype molecular system for establishing triplet state chemistry, materials based on molecular systems containing the benzophenone moiety as an integral part have not been exploited as generic host materials in phosphorescent organic light-emitting diodes (PhOLEDs). We have designed and synthesized three novel host materials, i.e., BP2-BP4, which contain benzophenone as the active triplet sensitizing molecular component. It is shown that their high band gap (3.91-3.93 eV) as well as triplet energies (2.95-2.97 eV) permit their applicability as universal host materials for blue, green, yellow, and red phosphors. While they serve reasonably well for all types of dopants, excellent performance characteristics observed for yellow and green devices are indeed the hallmark of benzophenone-based host materials. For example, maximum external quantum efficiencies of the order of 19.2% and 17.0% were obtained from the devices fabricated with yellow and green phosphors using BP2 as the host material. White light emission, albeit with rather poor efficiencies, has been demonstrated as a proof-of-concept by fabrication of co-doped and stacked devices with blue and yellow phosphors using BP2 as the host material.
authors.affiliation: Department of Chemistry, Indian Institute of Technology , Kanpur 208016, India.
authors.forename: Samik
authors.initials: S
authors.lastname: Jhulki
authors.affiliation: Department of Chemistry, Indian Institute of Technology , Kanpur 208016, India.
authors.forename: Saona
authors.initials: S
authors.lastname: Seth
authors.affiliation: Institute of Chemistry, Academia Sinica , Taipei, Taiwan 115, Republic of China.
authors.forename: Avijit
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: Institute of Chemistry, Academia Sinica , Taipei, Taiwan 115, Republic of China.
authors.forename: Tahsin J
authors.initials: TJ
authors.lastname: Chow
authors.affiliation: Department of Chemistry, Indian Institute of Technology , Kanpur 208016, India.
authors.forename: Jarugu Narasimha
authors.initials: JN
authors.lastname: Moorthy
keywords: PhOLED; band gap and phosphor; benzophenone; host materials; phosphorescence; triplet energy