title: Pyrene-Oxadiazoles for Organic Light-Emitting Diodes: Triplet to Singlet Energy Transfer and Role of Hole-Injection/Hole-Blocking Materials.
abstract: Three pyrene-oxadiazole derivatives were synthesized and characterized by optical, electrochemical, thermal, and theoretical investigations to obtain efficient multifunctional organic light emitting diode (OLED) materials. Synthesized molecules were used as emitters and electron transporters in three different device configurations, involving hole-injection/hole-blocking materials that showed good current and power efficiencies. To understand the underlying mechanisms involved in the application of these molecules as emitters and transporters, a detailed photophysical characterization of molecules 4-6 was carried out. The absorption, steady-state fluorescence, phosphorescence, fluorescence lifetime, and phosphorescence lifetime measurements were carried out. The high quantum yield and efficient reverse intersystem crossing leading to delayed fluorescence emission makes the molecule a good emitter, and the charge delocalization properties leading to excimer formation make them efficient electron transporters. Isoenergetic singlet and triplet states of the molecules make the reverse intersystem crossing feasible at room temperature even in the absence of thermal activation.
authors.affiliation: Crop Protection Chemicals Division and AcSIR, CSIR-Indian Institute of Chemical Technology , Uppal Road Tarnaka, Hyderabad 500007, India.
authors.forename: Swetha
authors.initials: S
authors.lastname: Chidirala
authors.affiliation: Optoelectronics Laboratory, Department of Physics, National Institute of Technology Karnataka , Surathkal, Mangalore 575025, India.
authors.forename: Hidayath
authors.initials: H
authors.lastname: Ulla
authors.affiliation: Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology , Uppal Road Tarnaka, Hyderabad 500007, India.
authors.forename: Anusha
authors.initials: A
authors.lastname: Valaboju
authors.affiliation: Optoelectronics Laboratory, Department of Physics, National Institute of Technology Karnataka , Surathkal, Mangalore 575025, India.
authors.forename: M Raveendra
authors.initials: MR
authors.lastname: Kiran
authors.affiliation: Crop Protection Chemicals Division and AcSIR, CSIR-Indian Institute of Chemical Technology , Uppal Road Tarnaka, Hyderabad 500007, India.
authors.forename: Maneesha Esther
authors.initials: ME
authors.lastname: Mohanty
authors.affiliation: Optoelectronics Laboratory, Department of Physics, National Institute of Technology Karnataka , Surathkal, Mangalore 575025, India.
authors.forename: M N
authors.initials: MN
authors.lastname: Satyanarayan
authors.affiliation: Optoelectronics Laboratory, Department of Physics, National Institute of Technology Karnataka , Surathkal, Mangalore 575025, India.
authors.forename: G
authors.initials: G
authors.lastname: Umesh
authors.affiliation: Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology , Uppal Road Tarnaka, Hyderabad 500007, India.
authors.forename: Kotamarthi
authors.initials: K
authors.lastname: Bhanuprakash
authors.affiliation: Crop Protection Chemicals Division and AcSIR, CSIR-Indian Institute of Chemical Technology , Uppal Road Tarnaka, Hyderabad 500007, India.|Network Institute for Solar Energy , New Delhi 110012, India.
authors.forename: Vaidya Jayathirtha
authors.initials: VJ
authors.lastname: Rao