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Kevin-Davis Richler

Publications and source records attributed to Kevin-Davis Richler.

2 recordsLinked to original sources

Influence of static disorder and polaronic band formation on interfacial electron transfer in organic photovoltaic devices

Understanding the interfacial charge-separation mechanism in organic photovoltaics requires, due to its high level of complexity, bridging between chemistry and physics. To elucidate the charge separation mechanism, we present a fully quantum dynamical simulation of a generic one-dimensional Hamiltonian, which physical parameters model prototypical PCBM or $\text{C}_{60}$ acceptor systems. We then provide microscopic evidence of the influence random static and dynamic potentials have on the interfacial charge-injection rate. In particular, we unveil that dynamic potentials, due to strong electron-vibration interactions, can lead to the formation of polaronic bands. Such dynamical potentials, when compared to random static potentials, can provide the main detrimental influence on the efficiency of the process of interfacial charge-separation.

cond-mat.str-el

Inhomogeneous dynamical mean field theory of the small polaron problem

We present an inhomogeneous dynamical mean field theory (I-DMFT) that is suitable to investigate electron-lattice interactions in non-translationally invariant and/or inhomogeneous systems. The presented approach, whose only assumption is that of a local, site-dependent self-energy, recovers both the exact solution of an electron in a generic external potential in the non-interacting limit and the DMFT solution for the small polaron problem in translationally invariant systems. To illustrate its full capabilities, we use I-DMFT to study the effects of defects embedded on a two-dimensional surface. The computed maps of the local density of states reveal Friedel oscillations, whose periodicity is determined by the polaron mass. This can be of direct relevance for the interpretation of scanning-tunneling microscopy (STM) experiments on systems with sizable electron-lattice interactions. Overall, the easy numerical implementation of the method, yet full self-consistency, allows one to study problems in real-space that were previously difficult to access.

cond-mat.mtrl-sci