JSC

Jsc, or short-circuit current density, is a parameter used primarily in photovoltaics to describe the current density through a solar cell when its terminals are shorted (voltage approximately zero). It is conventionally expressed in amperes per square meter (A/m^2) or, more commonly for small-area devices, in milliamperes per square centimeter (mA/cm^2). The total short-circuit current Isc is the product of Jsc and the cell area.

Measurement of Jsc is typically performed under Standard Test Conditions: an irradiance of 1000 W/m^2, a spectral distribution of AM1.5, and a cell temperature of 25°C. Jsc is obtained from the current–voltage curve by taking the current at V = 0. It is influenced by the incident light spectrum, intensity, and the cell’s quantum efficiency across wavelengths.

Jsc is related to the external quantum efficiency (EQE) of a device. A common approximation is Jsc ≈ q ∫ Φ(λ) · EQE(λ) dλ over the relevant spectrum, where q is the elementary charge and Φ(λ) is the photon flux. Thus, higher light intensity or better spectral response increases Jsc. In practice, Jsc often scales roughly linearly with light intensity and is a key contributor to the maximum achievable current, alongside open-circuit voltage and fill factor, in determining solar cell efficiency.

In addition to photovoltaics, the term Jsc may occasionally appear in discussions of short-circuit current density in other optoelectronic or photoelectrochemical contexts, but it is most commonly associated with solar cells. See also Isc, Voc, and the J–V characteristic curve.