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In this work, we present a thin-film GaAs solar cell employing via contacts for forming a back-contacted solar cell to eliminate light blocking effects and enhance photon recycling at the same time. The fabrication procedure and the characterization of the fabricated devices are discussed in this paper. From our measurement, a conversion efficiency of 6.5%, open circuit voltage of 0.95 V, and a current density of 8.6mA/cm2 under one-sun illumination were obtained in a 5×5 mm cell.

We investigate the photon recycling characteristics of single junction solar cells incorporating 50-pairs multiple quantum wells (MQW) to exploit the high radiative recombination rate in one-dimensional carrier-confinement structures. In particular, we systematically compare solar cells with monolithically grown distributed Bragg reflectors (DBRs), as well as selective filters (SFs) with cutoff wavelengths of 880, 910, and 930 nm under standard and concentrated illumination conditions. Optical confinement in the vertical direction is verified based on the reflective spectra and electroluminescence properties. Consequently, the photo-recycling effect manifests under concentrated conditions, where the maximal open circuit voltage difference, by 12mV under 200x illumination, is achieved for MQW solar cells incorporating both the DBR and the 910-nm-cutoff SF, compared to those without the DBR or SFs. It is also revealed that the fill factor (FF) is also affected by the photon recycling effect, where incorporating SF results in the FF enhancement compared to the counterpart without the SF and the enhancement is higher for those with DBRs than without the DBRs.