Disorder-driven doping activation in organic semiconductors

Conductivity doping of organic semiconductors is an essential prerequisite for many organic devices, but the specifics of dopant activation are still not well understood. Using many-body simulations that include Coulomb interactions and dopant ionization/de-ionization events explicitly we here show significant doping efficiency even before the electron affinity of the dopant exceeds the ionization potential of the organic matrix (p-doping), similar to organic salts. We explicitly demonstrate that the ionization of weak molecular dopants in organic semiconductors is a disorder-, rather than thermally induced process. Practical implications of this finding are a weak dependence of the ionized dopant fraction on the electron affinity of the dopant, and an enhanced ionization of the weak dopants upon increasing dopant molar fraction. As a result, strategies towards dopant optimization should aim for presently neglected goals, such as the binding energy in host-dopant charge-transfer states being responsible for the number of mobile charge carriers. Insights into reported effects are provided from the analysis of the density of states, where two novel features appear upon partial dopant ionization. The findings in this work can be used in the rational design of dopant molecules and devices

Interaction in Virtual Worlds: Application to Music Performers

We present am odel for the representation of the interactions between virtual hum an figures and virtual objects in 3D virtual scenes. These interactions can depend on externally provided inform ation not being lim ited in their com plexity. The representationm odel for virtual hum ans ism odular and provides tools for representation of the interaction know-how pre-requisite.Tim ng constraints are relevant in thism odel and concurrency and synchronism are used to insure the adequacy of the resulting anim ations of virtual hum ans and associated interacted objects. Resulting gestures are derived from an adapted application of Inverse Kinem aticsm; hods. Keywords: Virtua Scenes, Virtua Hum ans, Virtua Objects, Interaction, Inverse Kinem atics, Musician Sim u ation. 1

Simulating a Human Society: the Challenges

Simulating a human society is a very complex interdisciplinary problem. In this paper, we try to show some important aspects to create inhabited worlds where virtual people can interact, co-operate, perceive the world and the society. Main aspects are flexible motion control, perception of the real and the virtual world, and high-level behavior. Concepts are illustrated in the case-study of emergent crowds