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博士論文 / Development of Absorbing Materials for Perovskite Solar Cells ペロブスカイト型太陽電池に応用する吸収材料の開発

著者

書誌事項

タイトル

Development of Absorbing Materials for Perovskite Solar Cells

タイトル別名

ペロブスカイト型太陽電池に応用する吸収材料の開発

著者名

Lan Chunfeng

学位授与大学

九州工業大学 (大学ID:0071) (CAT機関ID:KI000844)

取得学位

博士(工学)

学位授与番号

甲生工第281号

学位授与年月日

2017-03-24

注記・抄録

Recently, halide perovskite solar cells have attracted much attention due to their high power conversion efficiency (PCE) and low cost. Their efficiency has been sharply improved from 3.8% to 22.1% in the last six years, making them as the promising next generation solar cells. However, the halide perovskite solar cells are facing several serious problems, such as request of further improvement efficiency and the lead pollution. These problems hinder the future commercialization of halide perovskite solar cells. How to solve these problems is still a challenge. The efficiency of perovskite solar cells is strongly affected by the quality of perovskite films, such as the crystallization and coverage, while the lead pollution is attributed to the halide perovskite absorbing materials. Therefore, this thesis mainly focuses on the morphology control of CH3NH3PbI3 to fabricate high-quality perovskite films with good crystallization and full coverage to improve the efficiency. We also design and synthesize new lead-free absorbing materials to avoid the lead pollution. In Chapter 1, the background of solar energy and photovoltaic technologies has been introduced. Furthermore, the recent challenges for the halide perovskite solar cells and the purpose of this thesis have been described. In Chapter 2, the experimental procedures, including general preparation and characterization of perovskite materials and electrodes, as well as devices used in this thesis have been summarized. In Chapter 3, a new method of concentration gradient controlled growth has been developed to prepare high-quality CH3NH3PbI3 perovskite films under ambient conditions. The two-step reactions were used with the concentration gradient of CH3NH3I (MAI) solutions, yielding the perovskite films with different crystallization and surface morphologies. In details, the first-step reaction between a low concentration MAI solution and the PbI2 films resulted in the formation of large-scale perovskite grains, and in the second-step reaction with a high concentration MAI solution we achieved a full coverage of the perovskite films. The large grain sizes of ca. 1.5 μm in the CH3NH3PbI3 perovskite films were obtained using the concentration gradient method, which means that the grain boundaries can be reduced. Meanwhile, spectral absorption in the short- wavelength region was enhanced in the concentration-gradient controlled perovskite films due to light scattering, which is considered to benefit the power conversion of solar cells. The perovskite solar cells fabricated using the concentration gradient controlled method showed higher photovoltaic performance than that by the traditional single solution method. In Chapter 4, the Pb-free composites of bismuth triiodide (BiI3) and layered perovskite (CH3NH3)3Bi2I9 (MBI) have been prepared by a simple solution method for thin film solar cells. It was found that the introduction of MBI significantly enhanced the crystallization and coverage of BiI3, meanwhile there was a multi-absorption phenomenon in the composite films. In addition, the band bending occurred at the BiI3-MBI interfaces, accompanying with the tuned energy levels in the composite films. The band bending was considered to benefit the efficient injection of excited electrons from absorbing layers into the electron transport layers. When 10-20% of MBI were used, the short circuit current density (Jsc) and open-circuit voltage (Voc) were improved in the composite solar cells. An enhancement of 65% of the PCE was achieved in the (BiI3)0.8(MBI)0.2 solar cells due to the multi-effects of the composite active layers. In Chapter 5, the Pb-free double perovskites La2NiMnO6 have been studied for potential application on solar cells. The rhombohedral and the monoclinic La2NiMnO6 were respectively formed under different conditions. The monoclinic La2NiMnO6 had an experimental bandgap (Eg) of 1.4 eV and valence band (VB) of -5.8 eV. Whereas, the rhombohedral La2NiMnO6 had an experimental Eg of 1.2 eV and VB of -5.7 eV. Both of them are suitable as visible light absorbers. Furthermore, the density function theory calculation confirmed that the theoretical bandgap of the monoclinic La2NiMnO6 was larger than that of the rhombohedral La2NiMnO6, which was mainly attributed to the B-site distortion. Simultaneously, the top of the VB of La2NiMnO6 mainly come from the interaction of Ni 3d orbitals and O 2p orbitals, whereas the bottom of the conduction band primarily come from the hybridization between Mn 3d and O 2p orbitals. The results of experimental and theoretical studies indicated that the monoclinic double perovskite La2NiMnO6 is a better candidate as absorbing material than the rhombohedral La2NiMnO6 for solar cells. Finally, general conclusions and future prospects have been presented. The investigations of Pb-based perovskites and Pb-free perovskites solar cells are still facing big challenges. The further studies including architectures designing of devices, recycling of Pb-based perovskites and development of new Pb-free perovskites with high performance are needed.

九州工業大学博士学位論文 学位記番号:生工博甲第281号 学位授与年月日:平成29年3月24日

1. Introduction|2. Experimental section for sample preparation, device fabrication and measurement|3. Concentration gradient controlled growth of large-grain CH3NH3PbI3 films and enhanced photovoltaic performance of solar cells in ambient conditions|4. Effect of lead-free (CH3NH3)3Bi2I9 perovskite addition on spectrum absorption and enhanced photovoltaic performance of bismuth triiodide solar cells|5. Investigation on structures, bandgaps and electronic structures of lead-free La2NiMnO6 double perovskites for potential application of solar cell

平成28年度

九州工業大学博士学位論文(要旨)学位記番号:生工博甲第281号 学位授与年月日:平成29年3月24日

目次

  1. 2017-10-02 再収集 / (index.pdf)

キーワード

Solar cells, Absorbing material, Perovskite, Microstructure control, Lead-free

各種コード

NII論文ID(NAID)

500001036624

NII著者ID(NRID)
  • 8000001141523
本文言語コード

eng

データ提供元

機関リポジトリ / NDLデジタルコレクション

博士論文 / 九州工業大学 / 工学

博士論文 / 九州工業大学

博士論文 / 工学

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