Modified Transport Model for Organic Diodes Considering the Neutral Condition and Two Types of Density of State

10.6122/CJP.20141027B

Muhammad Ammar Khan；Jiu-Xun Sun

Chinese Journal of Physics

53卷2期（2015 / 04 / 01）

179 - 194

英文

It is pointed out that organic diodes should satisfy a neutral condition as the applied voltage is zero. In order to consider the neutral condition, the trapped electrons in the energy gap are introduced for p-type materials based on recent work of Nicolai et al. [Nature Mater. (Lond.) 11, 882 (2012)]. In the case considering the neutral condition, the mobility should be treated as an exponential function of the root of the electric field. Whereas in the case not considering the neutral condition, the mobility can be treated as being independent of the electric field. A density of states (DOS) with exponential tail is proposed. The neutral models with the Gaussian and the new DOS are applied to four organic diodes. Through solving the drift-diffusion equation, the experimental current-voltage data can be well described. But the results based on the new DOS show a better agreement with the experimental data than the Gaussian DOS, and this implies the importance of the DOS with an exponential tail.