Impact of organic overlayers on a-Si:H/c-Si surface potential

Abstract
Bilayers of intrinsic and doped hydrogenated amorphous silicon, deposited on crystalline silicon (c-Si) surfaces, simultaneously provide contact passivation and carrier collection in silicon heterojunction solar cells. Recently, we have shown that the presence of overlaying transparent conductive oxides can significantly affect the c-Si surface potential induced by these amorphous silicon stacks. Specifically, deposition on the hole-collecting bilayers can result in an undesired weakening of contact passivation, thereby lowering the achievable fill factor in a finished device. We test here a variety of organic semiconductors of different doping levels, overlaying hydrogenated amorphous silicon layers and silicon-based hole collectors, to mitigate this effect. We find that these materials enhance the c-Si surface potential, leading to increased implied fill factors. This opens opportunities for improved device performance.

Citation
Seif JP, Niesen B, Tomasi A, Ballif C, De Wolf S (2017) Impact of organic overlayers on a-Si:H/c-Si surface potential. Applied Physics Letters 110: 151601. Available: http://dx.doi.org/10.1063/1.4980047.

Acknowledgements
The authors gratefully acknowledge the technical support of Cédric Bucher and Lionel Domon. This work was funded by the EuroTech Universities Alliance in the framework of the Interface Science for Photovoltaics initiative, by Axpo Naturstrom Fonds, by the European Commission (FP7 project HERCULES, Contract No. 608498; FP7 project CHEETAH, Contract No. 609788), by the Office fédéral de l'énergie (OFEN), and by the Fonds National Suisse (FNS) Reequip program (Grant Nos. 206021_139135 and 206021_133832). The research reported in this publication was supported by funding the from King Abdullah University of Science and Technology (KAUST).

Publisher
AIP Publishing

Journal
Applied Physics Letters

DOI
10.1063/1.4980047

Additional Links
http://aip.scitation.org/doi/10.1063/1.4980047

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