Although charge-carrier selectivity in conventional crystalline silicon (c-Si) solar cells is usually realized by doping Si, the presence of dopants imposes inherent performance limitations due to parasitic absorption and carrier recombination. The development of alternative carrier-selective contacts, using non-Si electron and hole transport layers, has the potential to overcome such drawbacks and simultaneously reduce the cost and/or simplify the fabrication process of c-Si solar cells. Nevertheless, devices relying on such non-Si contacts with power conversion efficiencies (PCEs) that rival their classical counterparts are yet to be demonstrated. In this study, one key element is brought forward toward this demonstration by incorporating low-pressure chemical vapor deposited ZnO as the electron transport layer in c-Si solar cells. Placed at the rear of the device, it is found that rather thick (75 nm) ZnO film capped with LiFx/Al simultaneously enables efficient electron selectivity and suppression of parasitic infrared absorption. Next, these electron-selective contacts are integrated in c-Si solar cells with MoOx-based hole-collecting contacts at the device front to realize full-area dopant-free-contact solar cells. In the proof-of-concept device, a PCE as high as 21.4% is demonstrated, which is a record for this novel device class and is at the level of conventional industrial solar cells.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): OSR-CRG URF/1/3383
Acknowledgements: The authors thank Vincent Paratte for amorphous silicon preparation and Christophe Allebé and Nicolas Badel from CSEM for the high-quality wet-processing and metallization. This project received funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 727523 (NextBase), as well as Swiss national science foundation under Ambizione Energy grant ICONS (PZENP2_173627) and the China Postdoctoral Science Foundation (15Z102060052 and 16Z102060054). Part of this research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award no. OSR-CRG URF/1/3383, as well as funding from Saudi Aramco.