Estimation of subcell photocurrent in IMM3J using LED bias light

The photocurrent (I_photo) of a subcell in the inverted metamorphic triple-junction (IMM3J) solar cells after irradiation was estimated from the light current-voltage (LIV) characteristics. By calculating the shunt and diode current, I_photo was obtained as a fitting parameter of the dependence of the short-circuit current on the intensity of LED bias light using a circuit simulator. Estimation of the I_photo of subcell from LIV characteristics facilitates understanding of a current-limiting subcell not using external quantum efficiency and the spectrum of solar simulator. In addition, the temperature dependency of the subcell I_photo in the IMM3J solar cells was measured using this technique.