Law in Disorder

A formal request by the theorists produces a stand-alone Solid-State Theory Group at Bell Labs. A summer visitor program leads several visiting theorists to conclude that localization occurred in Feher’s samples due to an electrostatic mechanism suggested by Nevill Mott. Anderson develops a theory for localization where the disorder in the positions of the dopants plays a crucial role. Mott champions Anderson’s theory and the Nobel Committee cites it when Anderson wins a share of the 1977 Nobel Prize with Mott and John Van Vleck. David Thouless re-ignites Anderson’s interest in localization and he leads the Gang of Four to develop a novel scaling theory of localization.

Site-Specific Chemical Doping Reveals Electron Atmospheres at the Surfaces of Organic Semiconductor Crystals

Chemical doping controls the electronic properties of organic semiconductors, but so far, doping protocols and mechanisms are less developed than in conventional semiconductors. Here we describe a unique, site-specific, n-type surface doping mechanism for single crystals of two benchmark organic semiconductors that produces dramatic improvement in electron transport and concurrently provides unprecedented evidence for doping-induced space charge. The surface doping chemistry specifically targets crystallographic step edges, which are known electron traps, simultaneously passivating the traps and releasing itinerant electrons. The effect on electron transport is profound: field effect electron mobility increases by as much as a factor of 10 and its temperature dependent behavior switches from thermally-activated to band-like. Our findings suggest new site-specific strategies to dope organic semiconductors that differ from the conventional redox chemistry of randomly distributed substitutional impurities. Critically, they also verify the presence of dopant-induced electron atmospheres, confirming long-standing expectations for organic systems from conventional solid-state theory.

Information and Statistical Measures in Classical vs. Quantum Condensed-Matter and Related Systems

The presented editorial summarizes in brief the efforts of ten (10) papers collected by the Special Issue (SI) “Condensed-Matter-Principia Based Information & Statistical Measures: From Classical to Quantum”. The SI called for papers dealing with condensed-matter systems, or their interdisciplinary analogs, for which well-defined classical statistical vs. quantum information measures can be inferred while based on the entropy concept. The SI has mainly been rested upon objectives addressed by an international colloquium held in October 2019, at the University of Science and Technology (UTP) Bydgoszcz, Poland (see http://zmpf.imif.utp.edu.pl/rci-jcs/rci-jcs-4/), with an emphasis placed on the achievements of Professor Gerard Czajkowski (PGC). PGC commenced his research activity with diffusion-reaction (open) systems under the supervision of Roman S. Ingarden (Toruń), a father of Polish synergetics, and original thermodynamic approaches to self-organization. The active cooperation of PGC mainly with German physicists (Friedrich Schloegl, Aachen; Werner Ebeling, Berlin) ought to be underlined. Then, the development of Czajkowski’s research is worth underscoring, moving from statistical thermodynamics to solid state theory, pursued in terms of nonlinear solid-state optics (Franco Bassani, Pisa), and culminating very recently with large quasiparticles, termed Rydberg excitons, and their coherent interactions with light.