Progress in triple-junction amorphous silicon alloy solar cells with improved current mismatch in component cells

Abstract

We have achieved a new world record stable efficiency of 11.8% for amorphous silicon alloy solar cells using a spectrum-splitting, triple-junction structure. In addition to our previously reported key factors leading to high performance multijunction solar cells, we have improved the current matching among the component cells. We have designed the triple structure such that the top cell, which usually exhibits the highest fill factor, remains to be the current-limiting cell in the degraded state. One critical requirement for achieving the desired current matching without sacrificing the triple cell current is to obtain a high quality narrow bandgap bottom cell capable of producing sufficient red current. Details on this narrow bandgap amorphous silicon germanium alloy cell as well as stability data on the triple-junction cell are presented.

Wide bandgap p-type nanocrystalline silicon oxide as window layer for high performance thin-film silicon multi-junction solar cells

“…The optimized p-SiC films have higher optical bandgap ( $ 2.0 eV) and lower absorption loss than p-pc-Si: H, resulting in higher V oc and better blue spectral response. It is interesting to note that V oc higher than 1 V can be achieved with oxygen-or carbon-free p-pc-Si:H in substrate-type a-Si:H solar cells [8,12,13]. A pure protocrystalline character is observed at the i/p interface, which results in low recombination at the i/p interface and high V oc [9].…”

A review of primary technologies of thin-film solar cells

“…Yang et al at USSC [20,21] 2013 Developed a triple-junction device using α-Si:H/μc-Si:H/μc-Si:H formation. 13.4% (M) Kim et al at LGEARI [22]…”

Amorphous Silicon–Based Solar Cells

“…Researchers exploit the substrate temperature effect on the band gap in device making. Wider band gap materials are useful in the top component cell of a triple-junction solar cell [76,77]. Narrower band gap a-Si is useful as the top cell i-layer of an a-Si/a-SiGe tandem cell.…”