The impact of controlled nanopatterning on the Ag back contact of an n-i-p a-Si:H solar cell was investigated experimentally and through electromagnetic simulation. Compared to a similar reference cell with a flat back contact, we demonstrate an efficiency increase from 4.5% to 6.2%, with a 26% increase in short circuit current density. Spectral response measurements show the majority of the improvement between 600 and 800 nm, with no reduction in photocurrent at wavelengths shorter than 600 nm. Optimization of the pattern aspect ratio using electromagnetic simulation predicts absorption enhancements over 50% at 660 nm.
Bibliographical noteFunding Information:
We gratefully acknowledge H. Zeijlemaker for FIB assistance and C.H.M. van der Werf for solar cell deposition. The Caltech portion of this work was supported by the Department of Energy under Contract Number DE-FG02-07ER46405. Work at AMOLF is part of the research program of FOM which is financially supported by NWO. This work is part of the Global Climate and Energy Project (GCEP). This work is also a part of NANONED, a technology program of the Dutch Ministry of Economic Affairs.