| About this Abstract |
| Meeting |
2011 Electronic Materials Conference
|
| Symposium
|
2011 Electronic Materials Conference
|
| Presentation Title |
KK5, A-Si / Si Nanowire Hybrid Photovoltaics |
| Author(s) |
Sourobh Raychaudhuri, Rene Lujan, Katherine Song, Chris Paulson, Robert A. Street |
| On-Site Speaker (Planned) |
Sourobh Raychaudhuri |
| Abstract Scope |
The trade-off between solar cell thickness and carrier collection efficiency places a practical limitation on planar amorphous Si (a-Si) photovoltaic devices which prevents them from efficiently absorbing light in the longer wavelengths. To address this issue we have devised a scheme where a thin a-Si cell is deposited over a disordered Si nanowire (NW) mat. The disordered geometry of the NW mat scatters light causing a photon to interact with multiple nanowires increasing the probability that it will be absorbed. The NW mat makes it possible to improve the absorption efficiency of the cell without increasing the cell thickness and thus results in enhanced absorption at the longer wavelengths. We fabricated and studied these a-Si / Si Nanowire hybrid structures. The NW mats are grown using the VLS technique with nanowire lengths of 5-10 microns. The nanowires are coated with 100-400 nm a-Si PIN solar cell structures. Top contact is achieved by using a transparent conducting oxide. We are able to grow disordered mats on a variety of substrates including silicon, glass and flexible stainless steel foil which allow for a variety of novel designs. We present electrical and optical characterization data for our NW hybrid photovoltaics. We will examine how disordered mat geometries can be optimized to impact cell performance. Our current device designs show a 10 fold increase in the absorption of red/infrared light (>700 nm) over comparable planar devices. We will also discuss the challenges in fabricating and optimizing these devices for efficient operation. Our experiments focus on device geometries that can be fabricated using techniques that are compatible with a-Si processing technologies. |
| Proceedings Inclusion? |
Undecided |