The semiconductivity of organic substances. Part 1

Abstract

An examination has been made of the effect of temperature on the d.c. electrical conductivity of a number of crystalline organic powders. Many substances show a semiconductivity possessing a definite activation energy E. In the uncompressed state, the " activation energy " E is largely influenced by crystal contacts. Under compression, a lower value of E is obtained which is probably characteristic of the crystals themselves. It is suggested that the excited orbitals of the 7~ electrons in the isolated molecule are combined to give non-localized orbitals stretching throughout the crystal. 2E is then the energy gap between the highest filled band or molecular level and the conduction band. Its value is discussed in terms of single electron transitions in the isolated molecule, and the overlap of 7~ orbitals between neighbouring molecules. The semiconductivity of three globular proteins is also examined in a preliminary fashion.

Sequence Dependent Hole Evolution in DNA

“…As was noted in [18], a well-determined linear structure of a DNA consisting of stacks of pyrimidine-purine bases resembles stacking in unidimensional aromatic crystals. Numerous discussions have been devoted to the problem of whether a DNA with its aromatic compounds in the shape of stacks of heterocyclic base pairs forms a profile of a potential energy along which a charged particle can be transferred over a large distance.…”

“…The hypothesis that a DNA may have conducting properties was first put forward in [18] shortly after the DNA helical structure had been discovered by Watson and Crick. As was noted in [18], a well-determined linear structure of a DNA consisting of stacks of pyrimidine-purine bases resembles stacking in unidimensional aromatic crystals.…”

Optical, electro-optic and optoelectronic properties of natural and chemically modified DNAs

“…The fact that the UVabsorption spectra of the A-and B-forms are practically the same strongly suggests that the electronic excitations primarily originate from the electrons in the basal planes rather than those involved in p z -delocalization in the perpendicular direction. 23 The circular dichroic (CD) spectra of Na þ DNA À and Q þ DNA À complexes in solution and in a dry film were studied by Tanaka and Okahata. 13 The authors demonstrated that the replacement of Na þ ions with Q þ ions did not change the conformation of the DNA backbone, and consequently, the basic features of the CD spectra did not change (Figure 3).…”

Flexible and Organic Neural Interfaces: A Review

“…Indeed, many organic compounds had been shown to have semiconducting [1] as well as photoconductive [2] properties, thus stimulating the interest of the physics and chemistry communities [3].…”