One-dimensional correlation in the dipolar Ising crystal tricyclohexylmethanol: crystal structure revisited and heat capacity

Voltage controlled bio-organic inverse phototransistor

Thin films of poly-d-lysine act as polar organic and are also light sensitive. The capacitance-voltage, current-voltage, and transistor behavior were studied to gauge the photoresponse of possible poly-d-lysine thin film devices both with and without methylene blue as an additive. Transistors fabricated from poly-d-lysine act as inverse phototransistors, i.e., the on-state current is greatest in the absence of illumination. The poly-d-lysine thin film capacitance and the transistor current decrease with illumination, both with and without methylene blue as an additive. This suggests that the unbinding of photo exciton is significantly hindered in this system which is supported by the significant charge carrier lifetime for poly-d-lysine films both with and without methylene blue. For the majority carrier, the transistor geometry appears to depend on the gate voltage; in other words, the majority carrier depends on the polarization of the poly-d-lysine films, both with and without methylene blue as an additive.

Organic ferroelectrics

Ferroelectricity results from one of the most representative phase transitions in solids, and is widely used for technical applications. However, observations of ferroelectricity in organic solids have until recently been limited to well-known polymer ferroelectrics and only a few low-molecular-mass compounds. Whereas the traditional use of dipolar molecules has hardly succeeded in producing ferroelectricity in general, here we review advances in the synthesis of new organic materials with promising ferroelectric properties near room temperature, using design principles in analogy to inorganic compounds. These materials are based on non-covalent molecules formed by two or more components, in which ferroelectricity arises either from molecular displacements or from the collective transfer of electrons or protons. The principle of using multi-component molecular compounds leads to a much broader design flexibility and may therefore facilitate the development of future functional organics.