兰州大学机构库 >材料与能源学院
宽带隙钙钛矿太阳电池的活性层调控和透明化制备研究
Alternative TitleThe Study of Active Layer Modulation and Transparentization Processing for Wide-bandgap Perovskite Solar Cells
楼俊杰
Subtype博士
Thesis Advisor秦勇
2023-09-04
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name工学博士
Degree Discipline材料物理与化学
Keyword宽带隙 wide-bandgap 钙钛矿太阳电池 perovskite solar cell 后处理 post-treatment 添加剂 additive 缓冲层 buffer layer 半透明 semi-transparent 叠层 tandem
Abstract

近年来,钙钛矿材料由于其优异的光电性能和可调节的带隙,吸引了科研工作者的大量关注。单结钙钛矿太阳电池(PSCs)的最佳光电转换效率(PCE)已达到26.0%。为了突破单结电池的效率极限,进一步提升太阳电池的PCE,构建钙钛矿基叠层太阳电池是理想的方案。叠层电池中,作为顶部光吸收层的宽带隙钙钛矿(带隙范围1.55~2.30 eV)是重要的组成部分。目前,最具代表性的叠层电池是两结、三结钙钛矿基叠层电池。对于三结叠层电池,纯溴基钙钛矿(带隙~2.3 eV)是合适的选择。由于钙钛矿体相和界面处非辐射载流子复合的影响,纯溴基PSCs的效率仍然偏低,有较大的提升空间。针对纯溴基PSCs中钙钛矿薄膜所存在的问题,本文采用薄膜优化策略,通过有机盐后处理方法(第一个工作)和添加剂方法(第二个工作)提升了纯溴基PSCs的性能。对于两结叠层电池,宽带隙钙钛矿(带隙~1.7 eV)是理想的材料。为了叠层应用而制备半透明宽带隙PSCs时,溅射透明电极会引起溅射损伤和电极、载流子传输层之间非理想接触等问题,导致器件性能下降。针对宽带隙PSCs透明化制备过程中的问题,本文采用缓冲层优化策略,通过设计缓冲层(第三个工作)和选择缓冲层(第四个工作)降低了半透明宽带隙PSCs中由于溅射透明电极所带来的不利影响。论文工作为高效两结或三结叠层电池的进一步研发打下了一定的基础。具体研究内容如下:

1. 优化钙钛矿薄膜,提升正式结构纯溴基PSCs的性能。无机CsPbBr3钙钛矿材料在稳定性方面具有很大优势。然而,钙钛矿体相和界面处的非辐射载流子复合,会显著降低CsPbBr3 PSCs的性能。针对钙钛矿薄膜所存在的问题,研究了有机盐溴化甲脒(FABr)后处理对CsPbBr3薄膜的影响。经过FABr后处理,FA+与Cs+间离子交换改变了钙钛矿薄膜的能级结构,在靠近Spiro-OMeTAD一侧减小与Spiro-OMeTAD的价带顶能级差,在靠近SnO2一侧形成附加电场,促进了载流子的提取。此外,这种方法还钝化了钙钛矿薄膜晶界和表面的缺陷,减少了缺陷相关的非辐射复合。经过FABr后处理,正式CsPbBr3 PSC的PCE从6.74%提升至8.25%。经过1000 h的存储稳定性测试(或者720 h的85oC下热稳定性测试),FABr处理和未处理器件的PCEs均能保持初始值的90%以上,表明FABr处理和未处理的CsPbBr3薄膜均具有优异的稳定性。

2. 优化钙钛矿薄膜,提升反式结构纯溴基PSCs的性能。FAPbBr3钙钛矿具有稳定性好、制备温度低等优势。然而,FAPbBr3薄膜制备过程中产生的缺陷会导致体相和界面处非辐射载流子复合。针对钙钛矿薄膜所存在的问题,研究了醋酸甲脒(FAAc)添加剂对钙钛矿薄膜的影响。FAAc钝化了FAPbBr3薄膜中的缺陷,减少了缺陷相关的非辐射复合。此外,FAAc的引入减小了FAPbBr3薄膜的表面粗糙度,有利于填充因子(FF)的改善。FAAc添加剂将反式FAPbBr3 PSC的PCE从5.30%提升至6.74%。经过864 h的存储稳定性测试,添加和未添加FAAc的PSCs的PCEs均能保持初始值的80%以上。经过624 h的85oC下热稳定性测试,添加FAAc的PSC的PCE保持初始值的37.9%,未添加FAAc的PSC的PCE保持初始值的27.6%。

3. 优化缓冲层,提升反式结构半透明宽带隙PSCs的性能。半透明宽带隙PSCs(~1.7 eV)在钙钛矿/硅两结叠层电池中的应用是目前研究的重点方向。制备半透明PSCs时,由溅射方法沉积的顶端透明电极会引起问题。一方面,溅射过程中产生的高能粒子会破坏已制备的功能层。另一方面,透明电极会与载流子传输层形成非理想的电学接触。针对电池透明化制备过程中存在的这些问题,研究了多层缓冲层对反式半透明PSCs性能的影响。反式宽带隙PSCs的最佳PCE达到20.06%。在此基础上,以ZnO,ZnO/BCP,ZnO/BCP/Ag为缓冲层构建半透明宽带隙PSCs。与ZnO和ZnO/BCP缓冲层相比,ZnO/BCP(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)/Ag多层缓冲层降低了电子传输层与透明电极间的接触电阻,促进了界面处的载流子传输。此外,ZnO/BCP/Ag多层缓冲层减少了电子传输层/透明电极界面处的非辐射复合。多层缓冲层的使用将反式半透明宽带隙PSC的PCE由7.88%提升至16.14%。通过在透明电极边缘蒸镀一圈Ag电极,半透明PSC的PCE被进一步提升至17.95%。由反式半透明宽带隙PSC(17.95%)与硅电池(22.57%)组成的四端钙钛矿/硅叠层电池的PCE为26.18%。

4. 优化缓冲层,提升正式结构半透明宽带隙PSCs的性能。在正式半透明PSCs中,MoOx缓冲层不仅会吸收近红外光而且会与钙钛矿反应。针对MoOx缓冲层存在的这些问题,研究了不同缓冲层对正式半透明PSCs性能的影响。正式宽带隙PSCs的最佳性能达到18.15%。在此基础上,以MoOx和NiOx为缓冲层构建半透明宽带隙PSCs。与MoOx缓冲层相比,NiOx缓冲层降低了空穴传输层与透明电极间的接触电阻,促进了界面处的载流子提取。与含MoOx缓冲层的正式半透明PSC(PCE: 10.27%)相比,含NiOx缓冲层的半透明PSC展现了更高的效率(PCE: 13.13%)和透射率(800~1200 nm范围增强了~3%),证明了NiOx作为缓冲层的可行性。

Other Abstract

Recently, perovskite materials have drawn much attention from researchers due to their excellent photoelectric properties and tunable bandgap. The best certified power conversion efficiency (PCE) of single-junction perovskite solar cells (PSCs) has been achieved 26.0%. For breaking up efficiency limit of single-junction solar cells and improving the PCE of solar cells, an ideal solution is to fabricate perovskite-based tandem solar cells. As top light absorption layers, wide-bandgap perovskites (range of bandgap: 1.55~2.30 eV) are an important component of tandem solar cells. Up to now, two-junction and triple-junction tandem solar cells are the most representative tandem solar cells. For triple-junction tandem solar cells, all bromide-based perovskites (bandgap of ≈ 2.3 eV) are appropriate choices. Due to the non-radiative carrier recombinations in the bulk and at the interface of the perovskite, the PCEs of all-bromide-based PSCs are still low, leaving large room for efficiency improvement. To solve the problem of perovskite thin film in all-bromide-based PSCs, this dissertation used thin film optimization strategy to improve the PCE of all-bromide-based PSCs through organic salt post-treatment method (the first work) and additive method (the second work). For two-junction tandem solar cells, wide-bandgap perovskites (bandgap of ≈ 1.7 eV) are ideal materials. During the preparation of semitransparent (ST) wide-bandgap PSCs for tandem application, sputtered transparent electrodes cause sputter damage and nonideal contact between electrodes and carrier transport layers, resulting in performance deterioration of devices. To solve the problem of transparentization processing for wide-bandgap PSCs, this dissertation used buffer layer optimization strategy to reduce negative effects of sputtered transparent electrodes on ST-PSCs via design of buffer layers (the third work) and selection of buffer layers (the fourth work). This dissertation lays the foundation for further research of efficient two-junction or triple-junction tandem solar cells. The specific research contents are shown in the following:

1. Optimizing perovskite thin film to improve the performance of normal all-bromide-based PSCs. Inorganic CsPbBr3 perovskite has huge advantage in stability. However, non-radiative carrier recombinations in the bulk and at the interface of the perovskite degrade the performance of CsPbBr3 PSCs. To solve the problems of perovskite thin film, we studied the effect of organic salt FABr post-treatment on CsPbBr3 thin film. After FABr post-treatment, ion exchange between FA+ and Cs+ changed energy-level structure of perovskite thin film, reduced valence bandgap maximum energy-level difference between perovskite and Spiro-OMeTAD on the Spiro-OMeTAD side, formed additional electric field on the SnO2 side, facilitating the extraction of carrier. In addition, this method passivated defects at grain boundaries and surface of perovskite thin film, reducing the defect-related non-radiative recombination. After FABr post-treatment, the PCE of normal CsPbBr3 PSC was improved from 6.74% to 8.25%. After 1000 h of storage stability test (or 720 h of thermal stability test at 85oC), the PCEs of control and FABr-treated devices maintained over 90% of their initial values, indicating excellent stability of control and FABr-treated CsPbBr3 film.

2. Optimizing perovskite thin film to improve the performance of inverted all-bromide-based PSCs. FAPbBr3 perovskite has advantages of good stability and low preparation temperature. However, defects generated during the deposition of FAPbBr3 thin film lead to non-radiative carrier recombinations in the bulk and at the interface of the perovskite. To solve the problem of perovskite thin film, we studied the effects of FAAc additive on perovskite thin film. FAAc passivated the defects in FAPbBr3 thin film, reducing defects-related non-radiative recombination. Besides, introduction of FAAc reduced surface roughness of FAPbBr3 thin film, benefiting for the improvement of fill factor (FF). FAAc additive improved the PCE of inverted FAPbBr3 PSC from 5.30% to 6.74%. After 864 h of storage stability test, the PCEs of control and FAAc-added devices maintained over 80% of their initial values. After 624 h of thermal stability test at 85oC, the PCE of FAAc-added device maintained 37.9% of its initial value, while the PCE of the control device maintained 27.6% of its initial value.

3. Optimizing buffer to improve the performance of inverted ST wide-bandgap PSCs. ST wide-bandgap PSC (≈ 1.7 eV) is currently a key research direction because of its application in two-junction perovskite/silicon tandem solar cells. During the preparation of ST-PSCs, top transparent electrodes deposited by magnetron sputtering will cause problems. On one hand, high-energy particles generated during sputtering process damage as-prepared functional layers. On the other hand, transparent electrodes form nonideal contact with carrier transport layer. To solve these problems related to transparentization processing of PSCs, we studied the effect of multi-layer buffer on the performance of inverted ST-PSCs. The optimized PCE of inverted wide-bandgap PSCs achieved 20.06%. Based on this kind of PSCs, ST wide-bandgap PSCs with ZnO, ZnO/BCP or ZnO/BCP/Ag as buffer were fabricated. Comparing with ZnO buffer and ZnO/BCP buffer, ZnO/BCP/Ag multi-layer buffer reduced the contact resistance between transparent electrode and electron transport layer, facilitating carrier transport at interface. In addition, ZnO/BCP/Ag multi-layer buffer reduced non-radiative recombination at the interface of transparent electrodes and electron transport layer. The application of multi-layer buffer improved the PCE of inverted ST wide-bandgap PSC from 7.88% to 16.14%. By evaporating Ag electrode along the edge of transparent electrode, the PCE of ST-PSC was increased to 17.95%. The PCE of four-terminal perovskite/silicon tandem cell containing an inverted ST wide-bandgap PSC (17.95%) and a silicon cell (22.57%) is 26.18%.

4. Optimizing buffer to improve the performance of normal ST wide-bandgap PSCs. In normal ST-PSCs, MoOx buffer not only absorbs near-infrared light but also reacts with perovskite. To solve the problems related to MoOx buffer, we studied the effect of different buffer layer on the performance of normal ST-PSCs. The optimized PCE of normal wide-bandgap PSCs achieved 18.15%. Based on this kind of PSCs, ST-PSCs with MoOx and NiOx buffer were fabricated. Compared with MoOx buffer, NiOx buffer reduced contact resistance between hole transport layer and transparent electrode, accelerating the extraction of carrier. Compared to ST-PSC with MoOx as buffer (PCE: 10.27%), ST-PSC with NiOx buffer exhibited higher efficiency (PCE: 13.13%) and transmittance (≈ 3% enhancement in the range of 800 to 1200 nm), proving the feasibility of NiOx buffer layer.

 

MOST Discipline Catalogue材料物理与化学
URL查看原文
Language中文
Other Code262010_120180906081
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/538360
Collection材料与能源学院
Affiliation
兰州大学材料与能源学院
Recommended Citation
GB/T 7714
楼俊杰. 宽带隙钙钛矿太阳电池的活性层调控和透明化制备研究[D]. 兰州. 兰州大学,2023.
Files in This Item:
There are no files associated with this item.
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Altmetrics Score
Google Scholar
Similar articles in Google Scholar
[楼俊杰]'s Articles
Baidu academic
Similar articles in Baidu academic
[楼俊杰]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[楼俊杰]'s Articles
Terms of Use
No data!
Social Bookmark/Share
No comment.
Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.