SnO2基鈣鈦礦太陽能電池界面調控與性能優化

汪志鵬; 李瑞; 張梅; 郭敏

doi:10.13374/j.issn2095-9389.2021.08.13.004

SnO₂基鈣鈦礦太陽能電池界面調控與性能優化

doi: 10.13374/j.issn2095-9389.2021.08.13.004

汪志鵬^{1, 2},
李瑞^{1, 2},
張梅^{1, 2},
郭敏^{1, 2, ,}

1.
北京科技大學冶金與生態工程學院，北京 100083
2.
北京科技大學鋼鐵冶金新技術國家重點實驗室，北京 100083

基金項目: 國家自然科學基金資助項目（51572020, 51772023）

詳細信息

通訊作者:
E-mail: guomin@ustb.edu.cn

中圖分類號: O472
計量
- 文章訪問數: 970
- HTML全文瀏覽量: 468
- PDF下載量: 158
- 被引次數: 0
出版歷程
- 收稿日期: 2021-08-13
- 網絡出版日期: 2021-11-11
- 刊出日期: 2023-02-01

Interface modification and performance optimization of SnO₂ based perovskite solar cells

WANG Zhi-peng^{1, 2},
LI Rui^{1, 2},
ZHANG Mei^{1, 2},
GUO Min^{1, 2
, ,}

1.
School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
2.
State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China

More Information

Corresponding author: E-mail: guomin@ustb.edu.cn

摘要

摘要: 近十余年來，鈣鈦礦太陽能電池光電轉換效率從3.8%提升至目前的25.5%，有望成為下一代商業用薄膜太陽能電池。然而，目前廣泛使用的TiO₂電子傳輸層電子遷移率低、退火溫度高、紫外光照穩定性差等特性使得TiO₂基鈣鈦礦太陽能電池性能，尤其是長期穩定性，面臨巨大挑戰。SnO₂由于良好的電子遷移率、適宜的能帶結構、簡單的低溫溶液合成以及穩定的化學結構等優點成為替代TiO₂電子傳輸層的首選。目前，調控SnO₂/鈣鈦礦以及鈣鈦礦/空穴傳輸層界面是SnO₂基鈣鈦礦太陽能電池性能優化的關鍵。鑒于此，在詳細介紹SnO₂電子傳輸層本體與表面，鈣鈦礦本體、晶界及表面缺陷類型及特征的基礎之上，重點總結了SnO₂/鈣鈦礦、鈣鈦礦/空穴傳輸層界面調控及性能提升的研究進展。最后，針對SnO₂基鈣鈦礦太陽能電池器件界面調控與性能優化的研究趨勢和發展方向做出展望。
- 鈣鈦礦太陽能電池 /
- SnO₂ /
- 缺陷鈍化 /
- 界面調控 /
- 性能優化
Abstract: Over the past decade, the power conversion efficiency of perovskite solar cells has increased from 3.8% to the current 25.5%, which is expected to become the next generation of commercial thin-film solar cells. However, the widely used TiO₂ electron transport layer has low electron mobility, requires a high annealing temperature, and has poor UV light stability, limiting the performance of TiO₂-based perovskite solar cells, especially long-term stability. SnO₂ is expected to be the first choice to replace TiO₂ electron transport layers because of its high electron mobility, suitable band structure, low-temperature solution synthesis, and stable chemical structure. Although the certified maximum efficiency of state-of-the-art SnO₂-based perovskite solar cells had exceeded 25%, it was still below its theoretical efficiency. Therefore, component engineering, interface engineering, solvent engineering, and other methods to improve the efficiency and stability of SnO₂-based perovskite solar cells have become a major research focus. Currently, regulating the SnO₂/perovskite and perovskite/hole transport layer interface is key to optimizing the performance of SnO₂-based perovskite solar cells. Most studies focused on improving the charge transport performance of SnO₂ and modifying the SnO₂/perovskite interface, while few studies have addressed defect passivation of the perovskite layer and the modification of the perovskite/SnO₂ interface. Therefore, it is essential to summarize the research progress of interface modification and performance optimization of SnO₂-based perovskite solar cells. This paper introduces the types and characteristics of defects in the bulk and surface of the SnO₂ electron transport layer, as well as defects in the bulk, grain boundaries, and surface of the perovskite film. The research progress of the interface modification (bulk and surface defect passivation) and performance improvement for the SnO₂ electron transport layer/perovskite and perovskite/hole transport layer are reviewed. Finally, the research directions of SnO₂-based perovskite solar cells on interface modification and performance optimization are presented.
- perovskite solar cells /
- SnO₂ /
- defect passivation /
- interface modification /
- performance optimization

HTML全文

圖 1 常見的電子傳輸材料的晶體結構與能帶圖. (a) SnO₂晶體結構；(b) 常見電子傳輸層LUMO與HOMO能級（相對于真空能級E_vac）。

Figure 1. Crystal structures and band diagrams of common electron transport materials: (a) SnO₂ crystal structure；(b) LUMO and HOMO energy levels of the electron transport layers (vs E_vac)

下載: 全尺寸圖片幻燈片

圖 2 SnO₂電子傳輸層常見的缺陷鈍化及界面調控示意圖（紫外臭氧處理、退火、摻雜、缺陷鈍化等）

Figure 2. Schematic diagram of common defect passivation and interface modification of the SnO₂ electron transport layer (UV ozone treatment, annealing, doping, defect passivation, etc.)

下載: 全尺寸圖片幻燈片

圖 3 (NH₄)₂S鈍化SnO₂電子傳輸層缺陷. (a) SnO₂缺陷鈍化后FTIR測試結果^[57]；(b) SnO₂缺陷鈍化原理圖^[57]；(c) 甘氨酸鈍化SnO₂缺陷的原理圖^[53]；(d) 3-(1-吡啶基)-1-丙烷磺酸鹽鈍化SnO₂缺陷的原理圖^[61].

Figure 3. SnO₂ electron transport layer defects passivated by (NH₄)₂S: (a) SnO₂ FTIR test results after defect passivation^[57]; (b) SnO₂ defect passivation principle diagram^[57]; (c)principle diagram SnO₂ defect passivated by glycine ^[53];(d) passivation mechanism diagram SnO₂ defects passivated by 3-(1-pyridyl)-1-propane sulfonate ^[61]

下載: 全尺寸圖片幻燈片

圖 6 鈣鈦礦缺陷鈍化原理圖. (a) 4-咪唑乙酸鹽酸鹽鈍化鈣鈦礦缺陷的原理圖^[67]；(b) PbI₂鈍化鈣鈦礦晶界^[83]

Figure 6. Schematic diagram of perovskite defect passivation: (a) schematic diagram of perovskite defects passivated by 4-imidazoleacetic acid hydrochloride ^[67]; (b) perovskite grain boundaries passivated by PbI₂ ^[83]

下載: 全尺寸圖片幻燈片

圖 4 鈣鈦礦常見的缺陷示意圖. (a) 鈣鈦礦完美晶體; (b) MA⁺空位; (c) I^?空位; (d) Pb²⁺間隙; (e) I₃^-間隙; (f) Pb—I反占位; (g) Pb²⁺空位; (h) 晶界; (i) 表面懸掛鍵

Figure 4. Schematic diagram of common defects in perovskite: (a) perfect perovskite crystal; (b) MA⁺ vacancy; (c) I^? vacancy; (d) Pb²⁺ interstitial; (e) I₃^- interstitial; (f) Pb—I antisite; (g) Pb²⁺ vacancy; (h) grain boundary; (i) surface dangling bond

下載: 全尺寸圖片幻燈片

圖 5 SnO₂基鈣鈦礦太陽能電池中鈣鈦礦常見的缺陷鈍化方法示意圖

Figure 5. Schematic diagram of common defect passivation methods in SnO₂-based perovskite solar cells

下載: 全尺寸圖片幻燈片

表 1 不同制備方法對SnO₂晶體結構、帶隙（E_g）、電子遷移率（μ）、缺陷態密度（N_t）的影響

Table 1. Influence of preparation methods on SnO₂ crystal structure, bandgap (E_g), electron mobility (μ), defect state density (N_t)

Preparation method	Crystal structure	E_g/eV	μ /(cm²·V^?1·s^?1)	Electrical conductivity/(S·cm^?1)	N_t /cm^?3	Reference
Sol-gel	Rutile		9.92×10^?4		1.93×10¹⁶	[43]
CBD	Rutile	3.92		2.4×10^?3	2.17×10¹⁵	[35]
ALD	Amorphous	3.68	2.44×10^?6	2.09×10^?4		[36]
Dual-source combustion	Rutile	4.03		3.2×10^?6		[40]
Electrodeposition	Rutile	3.67		6.0x10^?8		[42]

下載: 導出CSV

表 2 鈍化層鈍化SnO₂表面缺陷研究進展的總結：鈍化方式、鈍化物質/濃度、鈍化官能團、器件結構、有（W）無（WO）鈍化情況下器件性能參數

Table 2. Summary of research progress on SnO₂ surface defects passivated by the passivation layer: passivation materials, concentration, functional groups of the passivation material, device structure, device performance parameters with (W) without (WO) passivation.

Passivation materials	Device structure	PCE(WO/W)/%	Reference
Choline Chloride	Glass/ITO/Chol-SnO₂/MAPbI₃/Spiro-OMeTAD/Au	16.83/18.90	[12]
NPC₆₀-OH	Glass/ITO/SnO₂/ NPC₆₀-OH)/(FAMA)PbI₃/Spiro-OMeTAD/Ag	19.04/20.39	[62]
Dopamine	Glass/ITO/SnO₂/DA/MAPbI₃/Spiro-OMeTAD/Au	14.05/16.87	[65]
CH₃COOH	Glass/ITO/SnO₂/(CsFAMA)Pb(BrI)₃ /Spiro-OMeTAD/Au	18.84/20.56	[52]
Graphene quantum dots	Glass/ITO/SnO₂/GQDs/(FAMA)PbI_xCl_3-x/Spiro-OMeTAD/Ag	18.6/21.1	[69]
NH₂CHCOOH	Glass/ITO/SnO₂/Glycine/Cs_0.05FA_0.95-yMA_yPbI_1-xCl_x/Spiro-OMeTAD/Ag	18.82/20.63	[53]
KOH	Glass/ITO/SnO₂/KOH/CsPbI₂Br/carbon	8.59/10.7	[64]
Graphene quantum dots	Glass/FTO/GQDs：SnO₂/MAPbI₃/Spiro-OMeTAD/Au	13.61/16.54	[66]
Carbon quantum dots	Glass/FTO/SnO₂/GQDs/SnO₂/MAPbI₃/Spiro-OMeTAD/Ag	17.46/20.78	[70]
Fulleropyrrolidine(NMBF-Cl)	Glass/ITO/SnO₂/NMBF-Cl dimer/(FAPbI₃)_x(MAPbBr₃)_1?x/Spiro-OMeTAD/Ag	20.5/21.6	[71]
4-imidazoleacetic acid hydrochloride(ImAcHCl)	Glass/FTO/SnO₂/(FAPbI₃)_0.95(MAPbBr₃)_0.05/Spiro-MeOTAD/Au	19.53/20.96	[67]
NH₄F	Glass /ITO/SnO₂/(FAPbI₃)_0.95(MAPbBr₃)_0.05/spiro-OMeTAD/Au	22.4/23.2	[63]
potassium O-hexyl xanthate	Glass/ITO/SnO₂/MAPbI₃/Spiro-OMeTAD/Au	16.56/18.41	[72]
3-(1-pyridinio)-1-propanesulfonate	Glass/FTO/SnO₂/(CsFAMA)Pb(BrI)₃/Spiro-OMeTAD/Ag	19.63/21.43	[61]
CsAc	Glass/FTO/SnO₂/(FAPbI₃)_0.85(MAPbBr₃)_0.15/Spiro-OMeTAD/Au.	18.06/19.23	[73]
C₆₀ pyrrolidine tris-acid(CPTA)	PEN/ITO/SnO₂/CPTA/MAPbI₃/Spiro-OMeTAD/Au	15.35/18.36	[74]

下載: 導出CSV

表 3 SnO₂基鈣鈦礦太陽能電池中鈣鈦礦層缺陷鈍化及Perovskite/HTL界面調控的研究進展總結：鈍化類型、鈍化劑、器件結構、有（W）無（WO）鈍化情況下器件效率

Table 3. Summary of research progress on defect passivation of the perovskite layer and Perovskite/HTL interface regulation in SnO₂-based perovskite solar cells: passivation type, passivating agent, device structure, PCE with (W) without (WO) passivation

Passivation type	Passivating agent	Device structure	PCE(WO/W)/%	Reference
Bulk defect passivation	EDACl₂	Glass/ITO/SnO₂/ (EDACl₂)/ (Cs_0.15FA_0.85PbI_2.7Br_0.3)/Carbon	15.60/18.80	[81]
	Potassium-intercalated rubrene (K₂Rubrene)	Glass/ITO/SnO₂ QD/(FAMA)Pb(IBr)₃/Spiro-OMeTAD/Au	17.82/18.14	[80]
	PEAI	Glass/ITO/SnO₂/FA_1?xMA_xPbI₃/Spiro-OMeTAD/Au	20.95/23.53	[3]
	Pb(SCN)₂	Glass/ITO/SnO₂/FA_0.4MA_0.6PbI_2.8-xBr_0.2(SCN)_x/Spiro-OMeTAD/Ag	17.13/19.64	[13]
Grain boundary defect passivation	PbI₂	Glass/ITO/SnO₂/(FAPbI₃)_1-x(MAPbBr₃)_x/Spiro-OMeTAD/Au	17.61/19.55	[82]
	M13 bacteriophage	Glass/ITO/SnO₂/MAPbI₃(M13)/Spiro-OMeTAD/Au	17.1/19.7	[84]
	NAMI	Glass/FTO/SnO₂/Cs_0.05(MA_0.15FA_0.85)_0.95Pb(I_0.85Br_0.15)₃/(NMA)₂PbI₄/Spiro-OMeTAD/Au	18.75/20.41	[85]
	PMAI	Glass/ITO/SnO₂/FA_1–xMA_xPMA_yPbI₃/Spiro-OMeTAD/Au	20.93/23.32	[86]
Surface defect passivation	MASCN、FASCN	Glass/FTO/SnO₂/ FAPbI₃/Spiro-OMeTAD/Au	?/23.1	[88]
	PAI	Glass/ITO/SnO₂/ (CsFAMA)PbI₃/Spiro-OMeTAD/Au	16.85/20.53	[89]
	BAI	Glass/FTO/SnO₂/PCBM/BA_0.05(FA_0.83Cs_0.17)_0.91Pb(I_0.8Br_0.2)₃/Spiro-OMeTAD/Au	16.9/20.6	[87]

下載: 導出CSV

www.77susu.com

參考文獻(89)

[1]	Kojima A, Teshima K, Shirai Y, et al. Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. J Am Chem Soc, 2009, 131(17): 6050 doi: 10.1021/ja809598r
[2]	Kim H S, Lee C R, Im J H, et al. Lead iodide perovskite sensitized all-solid-state submicron thin film mesoscopic solar cell with efficiency exceeding 9%. Sci Rep, 2012, 2: 591 doi: 10.1038/srep00591
[3]	Jiang Q, Zhao Y, Zhang X W, et al. Surface passivation of perovskite film for efficient solar cells. Nat Photonics, 2019, 13(7): 460 doi: 10.1038/s41566-019-0398-2
[4]	National Renewable Energy Laboratory. Best research-cell efficiencies [J/OL]. Sciencepaper Online (2019-08-02) [2021-08-13].https://www.nrel.gov/ pv/assets/pdfs/best-research-cell-efficiencies
[5]	Li R, Zhang H Y, Han X, et al. Efficient nanorod array perovskite solar cells: A suitable structure for high strontium substitution in nature. ACS Appl Mater Interfaces, 2020, 12(9): 10515 doi: 10.1021/acsami.9b22556
[6]	Zhang H Y, Li R, Zhang M, et al. The effect of SrI₂ substitution on perovskite film formation and its photovoltaic properties via two different deposition methods. Inorg Chem Front, 2018, 5(6): 1354 doi: 10.1039/C8QI00131F
[7]	Zhang H Y, Li R, Liu W W, et al. Research progress in lead-less or lead-free three-dimensional perovskite absorber materials for solar cells. Int J Miner Metall Mater, 2019, 26(4): 387 doi: 10.1007/s12613-019-1748-2
[8]	Du C, Ma R X, Wang C Y, et al. Synthesis and properties of lead iodide for perovskite solar cells. Chin J Eng, 2019, 41(4): 454 杜晨, 馬瑞新, 王成彥, 等. 鈣鈦礦電池用碘化鉛的合成與性能. 工程科學學報, 2019, 41(4):454
[9]	Zhu Y, Du C, Wang S, et al. Research progress on the stability of perovskite solar cells. Chin J Eng, 2020, 42(1): 16 朱彧, 杜晨, 王碩, 等. 鈣鈦礦太陽能電池穩定性研究進展. 工程科學學報, 2020, 42(1):16
[10]	Xing G C, Mathews N, Sun S Y, et al. Long-range balanced electron- and hole-transport lengths in organic-inorganic CH₃NH₃PbI₃. Science, 2013, 342(6156): 344 doi: 10.1126/science.1243167
[11]	Son D Y, Im J H, Kim H S, et al. 11% efficient perovskite solar cell based on ZnO nanorods: An effective charge collection system. J Phys Chem C, 2014, 118(30): 16567 doi: 10.1021/jp412407j
[12]	Yan J J, Lin Z C, Cai Q B, et al. Choline chloride-modified SnO₂ achieving high output voltage in MAPbI₃ perovskite solar cells. ACS Appl Energy Mater, 2020, 3(4): 3504 doi: 10.1021/acsaem.0c00038
[13]	Yi H M, Duan L P, Haque F, et al. Thiocyanate assisted nucleation for high performance mix-cation perovskite solar cells with improved stability. J Power Sources, 2020, 466: 228320 doi: 10.1016/j.jpowsour.2020.228320
[14]	Zhang S C, Si H N, Fan W Q, et al. Graphdiyne: bridging SnO₂ and perovskite in planar solar cells. Angew Chem Int Ed Engl, 2020, 59(28): 11573 doi: 10.1002/anie.202003502
[15]	Feng J S, Yang Z, Yang D, et al. E-beam evaporated Nb₂O₅ as an effective electron transport layer for large flexible perovskite solar cells. Nano Energy, 2017, 36: 1 doi: 10.1016/j.nanoen.2017.04.010
[16]	Shin S S, Yang W S, Noh J H, et al. High-performance flexible perovskite solar cells exploiting Zn₂SnO₄ prepared in solution below 100?℃. Nat Commun, 2015, 6: 7410 doi: 10.1038/ncomms8410
[17]	Shin S S, Yeom E J, Yang W S, et al. Colloidally prepared La-doped BaSnO₃ electrodes for efficient, photostable perovskite solar cells. Science, 2017, 356(6334): 167 doi: 10.1126/science.aam6620
[18]	Bera A, Wu K W, Sheikh A, et al. Perovskite oxide SrTiO₃ as an efficient electron transporter for hybrid perovskite solar cells. J Phys Chem C, 2014, 118(49): 28494 doi: 10.1021/jp509753p
[19]	Wang T Y, Tai Q D, Guo X Y, et al. Highly air-stable tin-based perovskite solar cells through grain-surface protection by gallic acid. ACS Energy Lett, 2020, 5(6): 1741 doi: 10.1021/acsenergylett.0c00526
[20]	Tiwana P, Docampo P, Johnston M B, et al. Electron mobility and injection dynamics in mesoporous ZnO, SnO₂, and TiO₂ films used in dye-sensitized solar cells. ACS Nano, 2011, 5(6): 5158 doi: 10.1021/nn201243y
[21]	Liu P Y, Wang W, Liu S M, et al. Fundamental understanding of photocurrent hysteresis in perovskite solar cells. Adv Energy Mater, 2019, 9(13): 1803017 doi: 10.1002/aenm.201803017
[22]	Yin W J, Shi T T, Yan Y F. Unusual defect physics in CH₃NH₃PbI₃ perovskite solar cell absorber. Appl Phys Lett, 2014, 104(6): 063903 doi: 10.1063/1.4864778
[23]	Chen B, Yang M J, Priya S, et al. Origin of J-V hysteresis in perovskite solar cells. J Phys Chem Lett, 2016, 7(5): 905 doi: 10.1021/acs.jpclett.6b00215
[24]	Li Y, Zhu J, Huang Y, et al. Mesoporous SnO₂ nanoparticle films as electron-transporting material in perovskite solar cells. RSC Adv, 2015, 5(36): 28424 doi: 10.1039/C5RA01540E
[25]	Ke W J, Fang G J, Liu Q, et al. Low-temperature solution-processed tin oxide as an alternative electron transporting layer for efficient perovskite solar cells. J Am Chem Soc, 2015, 137(21): 6730 doi: 10.1021/jacs.5b01994
[26]	Yoo J J, Seo G, Chua M R, et al. Efficient perovskite solar cells via improved carrier management. Nature, 2021, 590(7847): 587 doi: 10.1038/s41586-021-03285-w
[27]	Jiang Q, Zhang X W, You J B. SnO₂: A wonderful electron transport layer for perovskite solar cells. Small, 2018, 14(31): e1801154 doi: 10.1002/smll.201801154
[28]	Jarzebski Z M, Morton J P. Physical properties of SnO₂ materials: III. optical properties. J Electrochem Soc, 1976, 123(10): 333C doi: 10.1149/1.2132647
[29]	Chen Y C, Meng Q, Zhang L R, et al. SnO₂-based electron transporting layer materials for perovskite solar cells: A review of recent progress. J Energy Chem, 2019, 35: 144 doi: 10.1016/j.jechem.2018.11.011
[30]	Jiang Q, Chu Z M, Wang P Y, et al. Planar-structure perovskite solar cells with efficiency beyond 21%. Adv Mater, 2017, 29(46): 1703852 doi: 10.1002/adma.201703852
[31]	Jiang Q, Zhang L Q, Wang H L, et al. Enhanced electron extraction using SnO₂ for high-efficiency planar-structure HC(NH₂)₂PbI₃-based perovskite solar cells. Nat Energy, 2017, 2: 16177 doi: 10.1038/nenergy.2016.177
[32]	Jung K H, Seok J Y, Lee S, et al. Solution-processed SnO₂ thin film for a hysteresis-free planar perovskite solar cell with a power conversion efficiency of 19.2%. J Mater Chem A, 2017, 5(47): 24790 doi: 10.1039/C7TA08040A
[33]	Yang G, Chen C, Yao F, et al. Effective carrier-concentration tuning of SnO₂ quantum dot electron-selective layers for high-performance planar perovskite solar cells. Adv Mater, 2018, 30(14): e1706023 doi: 10.1002/adma.201706023
[34]	Liu H R, Chen Z L, Wang H B, et al. A facile room temperature solution synthesis of SnO₂ quantum dots for perovskite solar cells. J Mater Chem A, 2019, 7(17): 10636 doi: 10.1039/C8TA12561A
[35]	Liu Q, Zhang X, Li C Y, et al. Effect of tantalum doping on SnO₂ electron transport layer via low temperature process for perovskite solar cells. Appl Phys Lett, 2019, 115(14): 143903 doi: 10.1063/1.5118679
[36]	Wang C L, Guan L, Zhao D W, et al. Water vapor treatment of low-temperature deposited SnO₂ electron selective layers for efficient flexible perovskite solar cells. ACS Energy Lett, 2017, 2(9): 2118 doi: 10.1021/acsenergylett.7b00644
[37]	Lv Y H, Wang P, Cai B, et al. Facile fabrication of SnO₂ nanorod arrays films as electron transporting layer for perovskite solar cells. Sol RRL, 2018, 2(9): 1800133 doi: 10.1002/solr.201800133
[38]	Gao C M, Yuan S, Cao B Q, et al. SnO₂ nanotube arrays grown via an in situ template-etching strategy for effective and stable perovskite solar cells. Chem Eng J, 2017, 325: 378 doi: 10.1016/j.cej.2017.05.085
[39]	Roose B, Baena J P C, G?del K C, et al. Mesoporous SnO₂ electron selective contact enables UV-stable perovskite solar cells. Nano Energy, 2016, 30: 517 doi: 10.1016/j.nanoen.2016.10.055
[40]	Liu X, Tsai K W, Zhu Z L, et al. A low-temperature, solution processable tin oxide electron-transporting layer prepared by the dual-fuel combustion method for efficient perovskite solar cells. Adv Mater Interfaces, 2016, 3(13): 1600122 doi: 10.1002/admi.201600122
[41]	Bu T L, Li J, Zheng F, et al. Universal passivation strategy to slot-Die printed SnO₂ for hysteresis-free efficient flexible perovskite solar module. Nat Commun, 2018, 9: 4609 doi: 10.1038/s41467-018-07099-9
[42]	Chen J Y, Chueh C C, Zhu Z L, et al. Low-temperature electrodeposited crystalline SnO₂ as an efficient electron-transporting layer for conventional perovskite solar cells. Sol Energy Mater Sol Cells, 2017, 164: 47 doi: 10.1016/j.solmat.2017.02.008
[43]	Yang D, Yang R X, Wang K, et al. High efficiency planar-type perovskite solar cells with negligible hysteresis using EDTA-complexed SnO₂. Nat Commun, 2018, 9: 3239 doi: 10.1038/s41467-018-05760-x
[44]	Ahmad W, Liu D T, Ahmad W, et al. Physisorption of oxygen in SnO₂ nanoparticles for perovskite solar cells. IEEE J Photovolt, 2019, 9(1): 200 doi: 10.1109/JPHOTOV.2018.2877002
[45]	Ji J, Liu X, Jiang H R, et al. Two-stage ultraviolet degradation of perovskite solar cells induced by the oxygen vacancy-Ti⁴⁺ states. iScience, 2020, 23(4): 101013 doi: 10.1016/j.isci.2020.101013
[46]	Ren X D, Yang D, Yang Z, et al. Solution-processed Nb: SnO₂ electron transport layer for efficient planar perovskite solar cells. ACS Appl Mater Interfaces, 2017, 9(3): 2421 doi: 10.1021/acsami.6b13362
[47]	Akin S. Hysteresis-free planar perovskite solar cells with a breakthrough efficiency of 22% and superior operational stability over 2000 H. ACS Appl Mater Interfaces, 2019, 11(43): 39998 doi: 10.1021/acsami.9b13876
[48]	Roose B, Friend R H. Extrinsic electron concentration in SnO₂ electron extracting contact in lead halide perovskite solar cells. Adv Mater Interfaces, 2019, 6(5): 1801788 doi: 10.1002/admi.201801788
[49]	Yang G, Lei H W, Tao H, et al. Reducing hysteresis and enhancing performance of perovskite solar cells using low-temperature processed Y-doped SnO₂ nanosheets as electron selective layers. Small, 2017, 13(2): 1601769 doi: 10.1002/smll.201601769
[50]	Wang E Q, Chen P, Yin X T, et al. Tailoring electronic properties of SnO₂ quantum dots via aluminum addition for high-efficiency perovskite solar cells. Sol RRL, 2019, 3(5): 1970055 doi: 10.1002/solr.201970055
[51]	Jiang E S, Ai Y Q, Yan J, et al. Phosphate-passivated SnO₂ electron transport layer for high-performance perovskite solar cells. ACS Appl Mater Interfaces, 2019, 11(40): 36727 doi: 10.1021/acsami.9b11817
[52]	Zhang X, Shi Z J, Lu H Z, et al. Highly efficient planar perovskite solar cells via acid-assisted surface passivation. J Mater Chem A, 2019, 7(39): 22323 doi: 10.1039/C9TA08042B
[53]	Du J H, Feng L P, Guo X, et al. Enhanced efficiency and stability of planar perovskite solar cells by introducing amino acid to SnO₂/perovskite interface. J Power Sources, 2020, 455: 227974 doi: 10.1016/j.jpowsour.2020.227974
[54]	Xiong L B, Qin M C, Yang G, et al. Performance enhancement of high temperature SnO₂-based planar perovskite solar cells: Electrical characterization and understanding of the mechanism. J Mater Chem A, 2016, 4(21): 8374 doi: 10.1039/C6TA01839D
[55]	Song Z L, Bi W B, Zhuang X M, et al. Low-temperature electron beam deposition of Zn-SnO_x for stable and flexible perovskite solar cells. Sol RRL, 2020, 4(2): 1900266 doi: 10.1002/solr.201900266
[56]	Gong H, Wang Y J, Teo S C, et al. Interaction between thin-film tin oxide gas sensor and five organic vapors. Sens Actuat B Chem, 1999, 54(3): 232 doi: 10.1016/S0925-4005(99)00119-7
[57]	Ai Y Q, Liu W Q, Shou C H, et al. SnO₂ surface defects tuned by (NH₄)₂S for high-efficiency perovskite solar cells. Sol Energy, 2019, 194: 541 doi: 10.1016/j.solener.2019.11.004
[58]	Hong J A, Jung E D, Yu J C, et al. Improved efficiency of perovskite solar cells using a nitrogen-doped graphene-oxide-treated tin oxide layer. ACS Appl Mater Interfaces, 2020, 12(2): 2417 doi: 10.1021/acsami.9b17705
[59]	Hui W, Yang Y G, Xu Q, et al. Red-carbon-quantum-dot-doped SnO₂ composite with enhanced electron mobility for efficient and stable perovskite solar cells. Adv Mater, 2020, 32(4): e1906374 doi: 10.1002/adma.201906374
[60]	Chen J B, Dong H, Zhang L, et al. Graphitic carbon nitride doped SnO₂ enabling efficient perovskite solar cells with PCEs exceeding 22%. J Mater Chem A, 2020, 8(5): 2644 doi: 10.1039/C9TA11344D
[61]	Choi K, Lee J, Kim H I, et al. Thermally stable, planar hybrid perovskite solar cells with high efficiency. Energy Environ Sci, 2018, 11(11): 3238 doi: 10.1039/C8EE02242A
[62]	Cao T, Chen K, Chen Q, et al. Fullerene derivative-modified SnO₂ electron transport layer for highly efficient perovskite solar cells with efficiency over 21. ACS Appl Mater Interfaces, 2019, 11(37): 33825 doi: 10.1021/acsami.9b09238
[63]	Jung E H, Chen B, Bertens K, et al. Bifunctional surface engineering on SnO₂ reduces energy loss in perovskite solar cells. ACS Energy Lett, 2020, 5(9): 2796 doi: 10.1021/acsenergylett.0c01566
[64]	Deng F, Li X T, Lv X D, et al. Low-temperature processing all-inorganic carbon-based perovskite solar cells up to 11.78% efficiency via alkali hydroxides interfacial engineering. ACS Appl Energy Mater, 2020, 3(1): 401
[65]	Hou M H, Zhang H J, Wang Z, et al. Enhancing efficiency and stability of perovskite solar cells via a self-assembled dopamine interfacial layer. ACS Appl Mater Interfaces, 2018, 10(36): 30607 doi: 10.1021/acsami.8b10332
[66]	Xia H R, Ma Z, Xiao Z, et al. Interfacial modification using ultrasonic atomized graphene quantum dots for efficient perovskite solar cells. Org Electron, 2019, 75: 105415 doi: 10.1016/j.orgel.2019.105415
[67]	Chen J Z, Zhao X, Kim S G, et al. Multifunctional chemical linker imidazoleacetic acid hydrochloride for 21% efficient and stable planar perovskite solar cells. Adv Mater, 2019, 31(39): e1902902 doi: 10.1002/adma.201902902
[68]	Tumen-Ulzii G, Matsushima T, Klotz D, et al. Hysteresis-less and stable perovskite solar cells with a self-assembled monolayer. Commun Mater, 2020, 1: 31 doi: 10.1038/s43246-020-0028-z
[69]	Pang S Z, Zhang C F, Zhang H R, et al. Boosting performance of perovskite solar cells with Graphene quantum dots decorated SnO₂ electron transport layers. Appl Surf Sci, 2020, 507: 145099 doi: 10.1016/j.apsusc.2019.145099
[70]	He L, Lv Z, Jiang H P, et al. Sandwich-like electron transporting layer to achieve highly efficient perovskite solar cells. J Power Sources, 2020, 453: 227876 doi: 10.1016/j.jpowsour.2020.227876
[71]	Wang H, Li F B, Wang P, et al. Chlorinated fullerene dimers for interfacial engineering toward stable planar perovskite solar cells with 22.3% efficiency. Adv Energy Mater, 2020, 10(21): 2000615 doi: 10.1002/aenm.202000615
[72]	Wang Z, Kamarudin M A, Huey N C, et al. Interfacial sulfur functionalization anchoring SnO₂ and CH₃NH₃PbI₃ for enhanced stability and trap passivation in perovskite solar cells. ChemSusChem, 2018, 11(22): 3941 doi: 10.1002/cssc.201801888
[73]	Zhao B X, Niu G D, Dong Q S, et al. The role of interface between electron transport layer and perovskite in halogen migration and stabilizing perovskite solar cells with Cs₄SnO₄. J Mater Chem A, 2018, 6(46): 23797 doi: 10.1039/C8TA09382B
[74]	Zhong M Y, Liang Y Q, Zhang J Q, et al. Highly efficient flexible MAPbI₃ solar cells with a fullerene derivative-modified SnO₂ layer as the electron transport layer. J Mater Chem A, 2019, 7(12): 6659 doi: 10.1039/C9TA00398C
[75]	Agiorgousis M L, Sun Y Y, Zeng H, et al. Strong covalency-induced recombination centers in perovskite solar cell material CH₃NH₃PbI₃. J Am Chem Soc, 2014, 136(41): 14570 doi: 10.1021/ja5079305
[76]	Steirer K X, Schulz P, Teeter G, et al. Defect tolerance in methylammonium lead triiodide perovskite. ACS Energy Lett, 2016, 1(2): 360 doi: 10.1021/acsenergylett.6b00196
[77]	Hu H L, Qin M C, Fong P W K, et al. Perovskite quantum wells formation mechanism for stable efficient perovskite photovoltaics-A real-time phase-transition study. Adv Mater, 2021, 33(7): e2006238 doi: 10.1002/adma.202006238
[78]	Yang I S, Park N G. Dual additive for simultaneous improvement of photovoltaic performance and stability of perovskite solar cell. Adv Funct Mater, 2021, 31(20): 2100396 doi: 10.1002/adfm.202100396
[79]	Jang Y W, Lee S, Yeom K M, et al. Intact 2D/3D halide junction perovskite solar cells via solid-phase in-plane growth. Nat Energy, 2021, 6(1): 63 doi: 10.1038/s41560-020-00749-7
[80]	Qin P L, Zhang J L, Yang G, et al. Potassium-intercalated rubrene as a dual-functional passivation agent for high efficiency perovskite solar cells. J Mater Chem A, 2019, 7(4): 1824 doi: 10.1039/C8TA09026B
[81]	Hou J, Deng F, Wu Q B, et al. Ethylenediamine chlorides additive assisting formation of high-quality formamidinium-caesium perovskite film with low trap density for efficient solar cells. J Power Sources, 2020, 449: 227484 doi: 10.1016/j.jpowsour.2019.227484
[82]	Chen Y C, Meng Q, Xiao Y Y, et al. Mechanism of PbI₂ in situ passivated perovskite films for enhancing the performance of perovskite solar cells. ACS Appl Mater Interfaces, 2019, 11(47): 44101 doi: 10.1021/acsami.9b13648
[83]	Ke W J, Xiao C X, Wang C L, et al. Employing lead thiocyanate additive to reduce the hysteresis and boost the fill factor of planar perovskite solar cells. Adv Mater, 2016, 28(26): 5214 doi: 10.1002/adma.201600594
[84]	Lin H S, Lee J M, Han J Y, et al. Denatured M13 bacteriophage-templated perovskite solar cells exhibiting high efficiency. Adv Sci, 2020, 7(20): 2000782 doi: 10.1002/advs.202000782
[85]	Liang L S, Luo H T, Hu J J, et al. Efficient perovskite solar cells by reducing interface-mediated recombination: A bulky amine approach. Adv Energy Mater, 2020, 10(14): 2000197 doi: 10.1002/aenm.202000197
[86]	Yang X Y, Fu Y Q, Su R, et al. Superior carrier lifetimes exceeding 6 μs in polycrystalline halide perovskites. Adv Mater, 2020, 32(39): 2002585 doi: 10.1002/adma.202002585
[87]	Wang Z P, Lin Q Q, Chmiel F P, et al. Efficient ambient-air-stable solar cells with 2D–3D heterostructured butylammonium-caesium-formamidinium lead halide perovskites. Nat Energy, 2017, 2: 17135 doi: 10.1038/nenergy.2017.135
[88]	Lu H Z, Liu Y H, Ahlawat P, et al. Vapor-assisted deposition of highly efficient, stable black-phase FAPbI₃ perovskite solar cells. Science, 2020, 370(6512): eabb8985 doi: 10.1126/science.abb8985
[89]	Yang N, Zhu C, Chen Y H, et al. An in situ cross-linked 1D/3D perovskite heterostructure improves the stability of hybrid perovskite solar cells for over 3000 h operation. Energy Environ Sci, 2020, 13(11): 4344 doi: 10.1039/D0EE01736A