Sputtered indium tin oxide as a recombination layer formed on the tunnel oxide/poly-Si passivating contact enabling the potential of efficient monolithic perovskite/Si tandem solar cells

摘要

We focus on utilizing sputtered indium tin oxide (ITO) as a recombination layer, having low junction damage to an n-type silicon solar cell with a front-side tunnel oxide passivating electron contact, thereby enabling the development of a high efficiency monolithic perovskite/Si tandem device. High transparency and low resistivity ITO films are deposited via low power DC magnetron sputtering at room temperature onto a front-side thin SiOx/n(+) poly-Si contact in a complete Cz n-Si cell with a back-side Al2O3/SiNx passivating boron-diffused p(+)-emitter on a random pyramid textured surface. We report the cell characteristics before and after ITO sputtering, and we find a cure at 250 degrees C in air is highly effective at mitigating any sputtering induced damage. Our ITO coated sample resulted in an implied open-circuit voltage (iV(oc)) of 684.7 +/- 11.3 mV with the total saturation current density of 49.2 +/- 14.8 fA/cm(2), an implied fill factor (iFF) of 81.9 +/- 0.8%, and a contact resistivity in the range of 60 m Omega-cm(2) to 90 m Omega-cm(2). After formation of a local Ag contact to the rear emitter and sputtered ITO film as the front-side contact without grid fingers, the pseudo-efficiency of 20.2 +/- 0.5% was obtained with the V-oc of 670.4 +/- 7 mV and pseudo FF of 77.3 +/- 1.3% under simulated one sun with the calculated short-circuit current density of 30.9 mA/cm(2) from the measured external quantum efficiency. Our modelling result shows that efficiency exceeding 25% under one sun is practically achievable in perovskite/Si tandem configuration using the ITO recombination layer connecting a perovskite top cell and a poly-Si bottom cell.