Integrated series-interconnected thin-film Si solar cells with 6 V and 12 V output voltage

A concept to increase the output voltage of solar cells using monolithically series-interconnected thin-film Si solar cells on SOI-wafers is presented. By using this concept 10 or 20 single cells (active areas: 0.4 cm/sup 2/ or 0.2 cm/sup 2/) have been processed on mono-x-Si SOI-wafers with a 15 /spl mu/m thick device layer. Two different kinds of SOI-material [/spl rho//sub p(Si active)/=(2...3) /spl Omega/cm and (0.1...0.9) /spl Omega/cm] have been used. A special technique permits the insulation of single cells on the burried oxide. Under insolation AM1.5G (100 mW/cm/sup 2/) open circuit voltage of 6.2 V (10 interconnected cells) and 12.6 V (20 interconnected cells), short circuit current densities of 23 mA/cm/sup 2/ and efficiencies up to 11% have been achieved. Measured IQE and emitter doping evaluation can be used to increase the efficiency furthermore.