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Transient photocurrent (TPC) is a measurement technique, typically employed in the physics of thin film 
A semiconductor is sandwiched between two extracting electrodes. When it is excited with a short pulse of light (as short as 100 femtoseconds), the photogenerated charges are extracted on the electrodes, resulting in a current, which is detected by an
OPV characterization techniques
Transient photocurrent in amorphous semiconductors
Semiconductor technology
semiconductors
A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...
. TPC allows to study the time-dependent (on a microsecond time scale) extraction of charges generated by photovoltaic effect in semiconductor devices, such as solar cells.
A semiconductor is sandwiched between two extracting electrodes. When it is excited with a short pulse of light (as short as 100 femtoseconds), the photogenerated charges are extracted on the electrodes, resulting in a current, which is detected by an oscilloscope
An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetiti ...
in form of voltage across a resistor
A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active el ...
. Since the excitation pulse is square, there are two ways to measure TPC: in a “light on” and a “light off” positions. In a “Light on”, the signal is recorded as soon as the excitation pulse is switched on, allowing to observe the build-up of charges on the electrode after the start of excitation. “Light off” measurements show how the charges decay after the pulse is switched off.
In contrast to transient photovoltage
ECHELON, originally a secret government code name, is a surveillance program (signals intelligence/SIGINT collection and analysis network) operated by the five signatory states to the UKUSA Security Agreement:Given the 5 dialects that use ...
, TPC measurements are conducted under short circuit condition and yield information about extractable charges, charge recombination and density of states. Quite often, TPC measurements help to build “ drift-diffusion” model which reflects trapping and detrapping of the photogenerated charges and the quality of contact between different layers.
TPC allows varying different measurement parameters, such as intensity or length of the light pulse, applied voltage, etc.
See also
*Time resolved microwave conductivity Time resolved microwave conductivity (TRMC) is an experimental technique used to evaluate the electronic properties of semiconductors. Specifically, it is used to evaluate a proxy for charge carrier mobility and a representative carrier lifetime fro ...
References
{{reflist *Guo, F. et al. A nanocomposite ultraviolet photodetector based on interfacial trap-controlled charge injection. Nat. Nanotechnol. 7, 798–802 (2012). *MacKenzie, R. C. I., Shuttle, C. G., Chabinyc, M. L. & Nelson, J. Extracting Microscopic Device Parameters from Transient Photocurrent Measurements of P3HT:PCBM Solar Cells. Adv. Energy Mater. 2, 662–669 (2012).External links
OPV characterization techniques
Transient photocurrent in amorphous semiconductors
Semiconductor technology