Spectral response measurements of multijunction solar cells with low shunt resistance and breakdown voltages

Abstract

Spectral response measurements of germanium-based triple-junction solar cells were performed under a variety of light and voltage bias conditions. Two of the three junctions exhibited voltage and light bias dependent artifacts in their measured responses, complicating the true spectral response of these junctions. To obtain more insight into the observed phenomena, a set of current-voltage measurement combinations were also performed on the solar cells under identical illumination conditions, and the data were used in the context of a diode-based analytical model to calculate and predict the spectral response behavior of each junction as a function of voltage. The analysis revealed that both low shunt resistance and low breakdown voltages in two of the three junctions influenced the measured quantum efficiency of all three junctions. The data and the modeling suggest that combination of current-voltage measurements under various light bias sources can reveal important information about the spectral response behavior in multijunction solar cells.

Boosting photocurrent of GaInP top-cell for current-matched III–V monolithic multiple-junction solar cells via plasmonic decahedral-shaped Au nanoparticles

“…Firstly, the Ge sub-cell with bandgap of 0.67 eV is not a suitable bottom candidate, which absorbs two times more photons than the top two junctions do [Friedman and Olson, 2001]. Secondly, the GaInP top cell with bandgap of 1.9 eV can only absorb the specific spectrum lower than 670 nm [Babaro et al, 2016]. Consequently, the present currentmismatched MTJ-SCs haven't reach the expected efficiency of the current matching models [Mellor et al, 2017].…”

“…As can be seen, the theoretical surface plasmon resonance peaks for Au decahedra, sphere and ellipsoid NPs are 547, 497 and 520 nm, respectively. The experimental counterpart of Au decahedra NPs is 546 nm too, and the increased extinction ability almost disappears for wavelength beyond 600 nm, which indicates that Au decahedra NPs only can boost the optical absorption enhancement of GaInP top-cell with the absorption edge of 670 nm [Babaro et al, 2016]. From the results obtained up till now, both the plasmonic peak and intensity of Au decahedral desire a better light trapping performance as contrast to the sphere and ellipsoid NPs, and thus foretelling a distinct photocurrent enhancement of SCs.…”

Proton‐Radiation Tolerant All‐Perovskite Multijunction Solar Cells

“…Non‐normalized data are depicted in Figures S2 and S3 (Supporting Information). Note that the Ge subcell EQE has been corrected from typical measurement artifacts that arise from low shunt resistances and low breakdown voltages prior to normalization following literature procedures, [ 44,45 ] as detailed in the Supporting Information.…”

Frequency response of the external quantum efficiency in multijunction solar cells

“…A suite of opto-electronic characterization techniques has been used in the past to explore the various characteristics of these cells. Extensive light bias and voltage bias dependent external quantum efficiency measurements [3–10], detailed current-voltage (I–V) characterization [11], and electroluminescence measurements [12,13] have traditionally been used to elucidate various artifacts and phenomena such as low shunt resistance effects [3,6,7,9,14,15], reverse breakdown voltage [3,4,16], and luminescence coupling (LC) [10,11,17–21] in these devices. Furthermore, new techniques such as electric modulus spectroscopy [22] have been used to observe charge coupling effects in Ge-based triple junction solar cells.…”