Tayagaki, T.T.TayagakiReichmuth, Kasimir S.Kasimir S.ReichmuthHelmers, HenningHenningHelmersSiefer, GeraldGeraldSiefer2022-03-0530.11.20192018https://publica.fraunhofer.de/handle/publica/25779710.24406/publica-r-25779710.1063/1.5046543We investigate the luminescent coupling (LC) effects in a four-junction GaInP/GaAs//GaInAsP/GaInAs concentrator solar cell based on transient open-circuit voltage (Voc) measurements under monochromatic illumination. Photocurrent generation in the non-absorbing GaInAs bottom subcell due to LC from upper subcells shows superlinear behavior with increasing light intensity. Along with this, a Voc enhancement is observed and quantified for illumination intensities that span almost six orders of magnitude. The Voc increase is explained and studied using a series-connected diode model including subcell shunt resistances, capacitances, and LC effects. The impact of unilluminated subcells on the subcell Voc determination is discussed for multi-junction solar cells. Finally, in the analysis of the LC generated photocurrent, namely, the coupling factor from the GaInAsP to the non-absorbing GaInAs subcell, a characteristic dependency on bias voltage is shown and explained by a result of competing photo- and electroluminescence mechanisms.enPhotovoltaikIII-V und Konzentrator-PhotovoltaikPower-by-Light530journal article