Exceptionally efficient organic light emitting devices using high refractive index substrates.

Organic light emitting devices (OLEDs) are now used in commercial cell phones and flat screen displays, but may become even more successful in lighting applications, in which large area, high efficiency, long lifetime and low cost are essential. Due to the relatively high refractive index of the organic layers, conventional planar bottom emitting OLEDs have a low outcoupling efficiency. Various approaches for enhancing the optical outcoupling efficiency of bottom emitting OLEDs have been introduced in the literature. In this paper we demonstrate a green bottom emitting OLED with a record external quantum efficiency (42%) and luminous efficacy (183 lm/W). This OLED is based on a high index substrate and a thick electron transport layer (ETL) which uses electrical doping. The efficient light outcoupling is modeled by optical simulations.

Posttraumatic soft tissue impingement of the ankle: arthroscopic findings and surgical outcomes.

UNLABELLED: Painful conditions and limited dorsal flexion of the ankle, which are the result of the friction of joint tissues and also the cause and the effect of altered joint biomechanics, are called ankle impingement syndromes. Post-traumatic ankle injures, like an ankle sprains or ankle fractures, are the main causes of impingement lesions, which result in chronic ankle pain. PURPOSE: To evaluate the results for patients treated arthroscopically for anterolateral soft tissue impingement after ankle injury. METHODS: Twelve patients underwent operative arthroscopy for anterolateral impingement between 2010 and 2012, A retrospective study with a mean follow up of 1 year. There were 7 females and 5 males, average age 44.1 years. RESULTS: Preoperative American ankle and foot score was average, 68 (63-71) points and after the operation 92 (87-95) points. CONCLUSION: Soft tissue impingement of the talocrural joint shows painful and limited dorsal flexion and plantar extension, effusion and joint line tenderness especially in the anterolateral gutter. Arthrofibrosis following ankle fractures causes an unfavorable surgical outcome, and arthroscopic debridement of fibrous tissue is an effective means of improving articular function.

Measurement and simulation of exciton decay times in organic light-emitting devices with different layer structures.

The decay time of an exciton depends on the coupling between the dipole oscillator and the optical environment in which it is placed. For an organic light-emitting device this environment is determined by the thin-film layer structure. The radiative decay competes with nonradiative decay channels and in this way influences the luminescent efficiency and the external quantum efficiency of the device. We describe a method to estimate the dependency of the exciton decay time and the luminescent efficiency on the thin-film stack and validate the results experimentally.