Tailoring Nano-Textures for Optimized Light In-Coupling in Liquid Phase Crystallized Silicon Thin-Film Solar Cells

Thin-film solar cells based on liquid phase crystallized silicon (LPC Si) with 8-20 mu m thick absorber layers demand for advanced light management to achieve high photocurrent densities. Open-circuit voltages (V-oc) > 600 mV underline the high silicon material quality of LPC silicon thin-films on nano-textured glass superstrates. We present a 500 nm-pitched sinusoidal nano-texture which outperforms larger pitched gratings with respect to light incoupling at the buried glass-silicon interface. In the wavelength range of interest reflection of incident light is minimized to values close to 4%, which is the reflection at the sun-facing air-glass interface. Further, the electronic material quality of sinusoidally textured devices is analyzed on basis of a comparison of maximum achieved open-circuit voltages on different texture types. The Voc on sinusoidally textured glass superstrates could be raised to 630 mV by changing the interlayer deposition method from a PVD to a PECVD process. Thus, we are able to unify high optical and electronic properties of silicon absorber layers on sinusoidaly textured glass substrates. These results constitute a crucial step toward fully exploiting the optical potential of LPC silicon thin-film solar cells.