Temperature dependent device characteristics of organic light-emitting devices

Abstract

Current-voltage characteristics of single and hetero-layer light-emitting devices with an aromatic diamine TPD as hole transport material and tris-8-hydroxyquinoline aluminum Alq as electron transport material and emitter have been investigated over a wide 3 temperature range and for various film thickness in order to identify the limiting mechanism: charge carrier transport or injection. From the observed thickness and temperature dependence, pure injection limitation can be ruled out as dominant mechanism. Instead, the m 1 voltage dependence of the current density can be well described by power laws j V with V corrected by the built-in potential with temperature dependent exponents m ranging from 4 to 25. This can be interpreted in terms of space charge limited currents SCLC in Alq with an exponential energetic distribution of traps where m is given by m E kT. A reasonable trap energy of 0.15-0.2 eV is 3 t obtained by a temperature dependent analysis of the I-V characteristics. However, the thickness dependence cannot be satisfactorily explained by the simple SCLC-model. This indicates that more sophisticated models are required.

Organic Materials and Thin‐Film Structures for Cross‐Point Memory Cells Based on Trapping in Metallic Nanoparticles

“…This variation is considerably less than the reported thermal behavior of charge injection into this material, as well as its mobility. [17] Both of these would be expected to vary by a factor of at least 50. The lack of strong temperature dependence suggests that the switching and transport processes are based on tunneling.…”

Influence of Temperature on the Steady State and Transient Luminance of an OLED Display

“…Indeed, it was found previously that the temperature distribution across an OLED display is non-uniform, time-varying and a function of the image content [4]- [11]. Considering on the one hand the relationship between temperature and the intensity of the light emission of an OLED [12]- [17] and on the other hand the influence of temperature on the TFT characteristic [18]- [21], the thermal behavior of an OLED display has a direct impact on the picture quality. These findings indicate that a thorough understanding of the link between temperature and the light emission of an OLED display is crucial to understand the display's shortcomings and eventually realize OLED displays that are suitable for the medical display market.…”

The nature of the electrical conduction and light emitting efficiency in organic semiconductors layers: The case of [m-MTDATA] – [NPB] – Alq3 OLED

“…Also the field emission over a barrier is studied [11]. Recently [12,13], a SCLC trap dependent model has been considered again and the problem remains an open question.…”