Symmetric Dopant‐Free Si Solar Cells Enabled by TiOx Nanolayers: An In‐Depth Study on Bipolar Carrier Selectivity
Abstract High‐efficiency solar cells require two contact structures, engineered for efficient extraction of photogenerated holes and electrons at the respective electrodes. Herein, crystalline Si solar cell featuring hole‐ and electron‐selective passivating contacts composed entirely of a single mat...
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Wiley
2025-01-01
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| Series: | Advanced Science |
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| Online Access: | https://doi.org/10.1002/advs.202410179 |
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| author | Takuya Matsui Shohei Fukaya Shona McNab James McQueen Kazuhiro Gotoh Hitoshi Sai Noritaka Usami Ruy Sebastian Bonilla |
| author_facet | Takuya Matsui Shohei Fukaya Shona McNab James McQueen Kazuhiro Gotoh Hitoshi Sai Noritaka Usami Ruy Sebastian Bonilla |
| author_sort | Takuya Matsui |
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| description | Abstract High‐efficiency solar cells require two contact structures, engineered for efficient extraction of photogenerated holes and electrons at the respective electrodes. Herein, crystalline Si solar cell featuring hole‐ and electron‐selective passivating contacts composed entirely of a single material, amorphous titanium oxide (TiOx), without extrinsic doping is demonstrated. The hole/electron selectivity of the TiOx layers (≈5 nm) is tailored by the oxidation process and the choice of Ti precursor in the atomic layer deposition (ALD). Ex situ and in situ X‐ray photoelectron spectroscopy measurements elucidate that the hole‐selective TiOx induces significant band bending in the Si (Φ≈0.7 eV), generating a p‐type inversion layer in the n‐Si absorber. The electron‐selective TiOx induces a smaller band bending of Φ<0.35 eV. This clarifies that the bipolar carrier selectivity of TiOx is associated with the different amount of negative fixed charges generated during the ALD process, depending on the choice of Ti precursor and oxidant. In addition, the growth of a hydrogen‐containing SiOy nanolayer (≈1‐1.5 nm) at the Si/TiOx interface during postdeposition oxidation is crucial for providing chemical passivation in both types of TiOx. These findings pave the way for a deeper understanding of the charge generation mechanism and chemistry at the Si/metal oxide interfaces. |
| format | Article |
| id | doaj-art-7120d74bd2b043dba37afb741b6452b2 |
| institution | Kabale University |
| issn | 2198-3844 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Wiley |
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| spelling | doaj-art-7120d74bd2b043dba37afb741b6452b22025-01-20T13:04:19ZengWileyAdvanced Science2198-38442025-01-01123n/an/a10.1002/advs.202410179Symmetric Dopant‐Free Si Solar Cells Enabled by TiOx Nanolayers: An In‐Depth Study on Bipolar Carrier SelectivityTakuya Matsui0Shohei Fukaya1Shona McNab2James McQueen3Kazuhiro Gotoh4Hitoshi Sai5Noritaka Usami6Ruy Sebastian Bonilla7Renewable Energy Research Center National Institute of Advanced Industrial Science and Technology (AIST) 1‐1‐1 Umezono Tsukuba Ibaraki 305‐8568 JapanRenewable Energy Research Center National Institute of Advanced Industrial Science and Technology (AIST) 1‐1‐1 Umezono Tsukuba Ibaraki 305‐8568 JapanDepartment of Materials University of Oxford Parks Rd Oxford OX1 3PH UKDepartment of Materials University of Oxford Parks Rd Oxford OX1 3PH UKGraduate School of Engineering Nagoya University Furo‐cho, Chikusa‐ku Nagoya 464‐8603 JapanRenewable Energy Research Center National Institute of Advanced Industrial Science and Technology (AIST) 1‐1‐1 Umezono Tsukuba Ibaraki 305‐8568 JapanGraduate School of Engineering Nagoya University Furo‐cho, Chikusa‐ku Nagoya 464‐8603 JapanDepartment of Materials University of Oxford Parks Rd Oxford OX1 3PH UKAbstract High‐efficiency solar cells require two contact structures, engineered for efficient extraction of photogenerated holes and electrons at the respective electrodes. Herein, crystalline Si solar cell featuring hole‐ and electron‐selective passivating contacts composed entirely of a single material, amorphous titanium oxide (TiOx), without extrinsic doping is demonstrated. The hole/electron selectivity of the TiOx layers (≈5 nm) is tailored by the oxidation process and the choice of Ti precursor in the atomic layer deposition (ALD). Ex situ and in situ X‐ray photoelectron spectroscopy measurements elucidate that the hole‐selective TiOx induces significant band bending in the Si (Φ≈0.7 eV), generating a p‐type inversion layer in the n‐Si absorber. The electron‐selective TiOx induces a smaller band bending of Φ<0.35 eV. This clarifies that the bipolar carrier selectivity of TiOx is associated with the different amount of negative fixed charges generated during the ALD process, depending on the choice of Ti precursor and oxidant. In addition, the growth of a hydrogen‐containing SiOy nanolayer (≈1‐1.5 nm) at the Si/TiOx interface during postdeposition oxidation is crucial for providing chemical passivation in both types of TiOx. These findings pave the way for a deeper understanding of the charge generation mechanism and chemistry at the Si/metal oxide interfaces.https://doi.org/10.1002/advs.202410179atomic layer depositioncarrier selectivitypassivating contactsiliconsolar celltitanium oxide |
| spellingShingle | Takuya Matsui Shohei Fukaya Shona McNab James McQueen Kazuhiro Gotoh Hitoshi Sai Noritaka Usami Ruy Sebastian Bonilla Symmetric Dopant‐Free Si Solar Cells Enabled by TiOx Nanolayers: An In‐Depth Study on Bipolar Carrier Selectivity Advanced Science atomic layer deposition carrier selectivity passivating contact silicon solar cell titanium oxide |
| title | Symmetric Dopant‐Free Si Solar Cells Enabled by TiOx Nanolayers: An In‐Depth Study on Bipolar Carrier Selectivity |
| title_full | Symmetric Dopant‐Free Si Solar Cells Enabled by TiOx Nanolayers: An In‐Depth Study on Bipolar Carrier Selectivity |
| title_fullStr | Symmetric Dopant‐Free Si Solar Cells Enabled by TiOx Nanolayers: An In‐Depth Study on Bipolar Carrier Selectivity |
| title_full_unstemmed | Symmetric Dopant‐Free Si Solar Cells Enabled by TiOx Nanolayers: An In‐Depth Study on Bipolar Carrier Selectivity |
| title_short | Symmetric Dopant‐Free Si Solar Cells Enabled by TiOx Nanolayers: An In‐Depth Study on Bipolar Carrier Selectivity |
| title_sort | symmetric dopant free si solar cells enabled by tiox nanolayers an in depth study on bipolar carrier selectivity |
| topic | atomic layer deposition carrier selectivity passivating contact silicon solar cell titanium oxide |
| url | https://doi.org/10.1002/advs.202410179 |
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