Energetic Disorder, Spatial Correlations, and the High-Field Mobility of Injected Charge Carriers in Organic Solids

In a large class of disordered organic solids, the observed field and temperature dependence of the mobility of photoinjected charge carriers arises from specific statistical features of the disordered potential energy landscape through which they move. In materials with polar constituents, energy fluctuations exhibit strong spatial correlations, with deep energetic valleys developing only over large length scales. We present a scaling analysis that shows how the hierarchical field-induced flattening of fluctuations of different magnitudes gives rise to field dependent (e.g., Poole-Frenkel type) mobilities characteristic of the spatial correlations from which they arise.