Current-voltage characteristic

Current-voltage characteristics of four components

The current-voltage characteristic curve (also called IU characteristic , current-voltage curve or also called UI diagram ) describes the relationship between electrical current and voltage in two-pole electrical components such as resistors , solar cells , accumulators and diodes .

In the case of ion channels , the current-voltage curve describes the relationship between membrane potential (or holding potential) and current through the membrane (in the case of whole-cell recordings) or the ion channel (in the case of single-channel measurements), see patch clamp .

Basics

non-linear characteristic of a solar cell

According to Thévenin's theorem , any system of voltage sources and (complex) resistances can be modeled as a two-pole electrical component. It is therefore also possible to record current-voltage characteristics of more complex assemblies.

In the simplest case, the characteristic curve is linear, especially if the internal resistance of the element is an ohmic resistance . This is the case, for example, when an ideal voltage source is connected in series with a resistor.

In the case of semiconductors such as the ideal diode, however, a curved, non-linear characteristic is desired. Even non-ideal voltage sources behave nonlinearly to varying degrees.

If the straight line and the characteristic curve are only intersected once, one speaks of open-circuit voltage and of short-circuit current . ${\ displaystyle U = 0}$${\ displaystyle I = 0}$${\ displaystyle I = 0}$${\ displaystyle U = 0}$

Measurement method

Basically, the same characteristic can be determined in two ways:

1. In the potentiostatic case, an initial voltage is applied to the electrodes at one point in time . The applied voltage is then gradually increased until the final voltage is reached .${\ displaystyle t_ {0}}$${\ displaystyle U_ {1}}$${\ displaystyle U_ {2}}$
2. In the galvanostatic case, a current is excited, which is then gradually increased until the final current is reached.${\ displaystyle I_ {1}}$${\ displaystyle I_ {2}}$

These measurement methods are used, among other things, in analog signature analysis , a test method from electronics manufacturing and repair.