Symmetric Dopant-Free Si Solar Cells Enabled by TiO x Nanolayers: An In-Depth Study on Bipolar Carrier Selectivity.

Autor: Matsui T; Renewable Energy Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568, Japan.; Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan., Fukaya S; Renewable Energy Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568, Japan.; Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan., McNab S; Department of Materials, University of Oxford, Parks Rd, Oxford, OX1 3PH, UK., McQueen J; Department of Materials, University of Oxford, Parks Rd, Oxford, OX1 3PH, UK., Gotoh K; Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan., Sai H; Renewable Energy Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568, Japan., Usami N; Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan., Bonilla RS; Department of Materials, University of Oxford, Parks Rd, Oxford, OX1 3PH, UK.
Jazyk: angličtina
Zdroj: Advanced science (Weinheim, Baden-Wurttemberg, Germany) [Adv Sci (Weinh)] 2024 Nov 28, pp. e2410179. Date of Electronic Publication: 2024 Nov 28.
DOI: 10.1002/advs.202410179
Abstrakt: 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 (TiO x ), without extrinsic doping is demonstrated. The hole/electron selectivity of the TiO x 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 TiO x 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 TiO x induces a smaller band bending of Φ<0.35 eV. This clarifies that the bipolar carrier selectivity of TiO x 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 SiO y nanolayer (≈1-1.5 nm) at the Si/TiO x interface during postdeposition oxidation is crucial for providing chemical passivation in both types of TiO x . These findings pave the way for a deeper understanding of the charge generation mechanism and chemistry at the Si/metal oxide interfaces.
(© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)
Databáze: MEDLINE
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