Until now acid-base diodes and transistors applied strong mineral acids and bases
exclusively. In this work properties of electrolyte diodes with weak electrolytes
are studied and compared with those of diodes with strong ones to show the advantages
of weak acids and bases in these applications. The theoretical model is a one dimensional
piece of gel containing fixed ionizable groups and connecting reservoirs of an acid
and a base. The electric current flowing through the gel is measured as a function
of the applied voltage. The steady-state current-voltage characteristic (CVC) of such
a gel looks like that of a diode under these conditions. Results of our theoretical,
numerical, and experimental investigations are reported in two parts. In this first,
theoretical part governing equations necessary to calculate the steady-state CVC of
a reverse-biased electrolyte diode are presented together with an approximate analytical
solution of this reaction-diffusion-ionic migration problem. The applied approximations
are quasielectroneutrality and quasiequilibrium. It is shown that the gel can be divided
into an alkaline and an acidic zone separated by a middle weakly acidic region. As
a further approximation it is assumed that the ionization of the fixed acidic groups
is complete in the alkaline zone and that it is completely suppressed in the acidic
one. The general solution given here describes the CVC and the potential and ionic
concentration profiles of diodes applying either strong or weak electrolytes. It is
proven that previous formulas valid for a strong acid-strong base diode can be regarded
as a special case of the more general formulas presented here. (c) 2005 American Institute
of Physics.
