原子層沉積之氧化錫薄膜在鈣鈦礦太陽能電池之電子傳導層與阻氣膜應用研究

Atomic-layer-deposited tin oxide thin films as electron-injection and gas-barrier layer for organic-inorganic hybrid lead halide perovskite solar cells

何孟諭(Meng-Yu Ho)

指導教授 ： 蔡豐羽

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202104406

摘要

近年迅速發展的有機無機混合鈣鈦礦太陽能電池(perovskite solar cells, 或PSC)，雖具有龐大商機潛力，但因其鈣鈦礦主動層的不穩定性而限制了其應用，極需低溫製程且具優異阻氣性能薄膜做為其封裝材料及功能性材料，以達到符合實用需求之使用壽命。為達到此目標，本研究以原子層沈積技術(atomic layer deposition, 或ALD) 於低溫製備同時具有阻氣性與電子傳輸性質之氧化錫(SnOx)薄膜，並驗證其做為鈣鈦礦太陽能電池之電子傳輸層(electron-transporting layer, 或ETL)之效能。
本研究開發SnOx薄膜之ALD低溫製程，並探討製程溫度與氧化劑(H2O和H2O2)對其阻氣性和ETL特性之影響。在製程溫度的影響方面，較低的沉積溫度(低至60 °C)使 ALD SnOx具有較平整的表面形態和較低的氣體滲透率(WVTR低至1.3 × 10-2 g m-2 day-1)。在氧化劑前驅物種類的影響方面，以較高反應性的雙氧水取代水，可以降低SnOx的表面粗糙度並提升阻氣性能。X 射線光電子能譜和紫外-可見光譜分析結果顯示，當使用雙氧水作為氧化劑時，SnOx薄膜中的SnO2比率提升，穿透度增加，有利於其電子傳輸與減少光吸收量。太陽能電池元件實驗結果顯示，降低沉積溫度、以高反應性H2O2作為氧化劑、整適當的SnOx薄膜厚度、增加H2O2劑量並在SnOx與鈣鈦礦層之間的介面插入鈍化層後，電池性能得以提升，在ETL最高製程溫度僅為75°C時，最佳效率可達13.76%。

關鍵字

原子層沉積技術 ； 鈣鈦礦太陽能電池 ； 氧化錫 ； 低溫製程

並列摘要

This study developed low-temperature atomic layer deposition (ALD) techniques to fabricate tin oxide (SnOx) thin films for use as an electron-transporting layer (ETL) for perovskite solar cell (PSC) devices, aiming to obtain both adequate gas barrier property and excellent ETL functions in the SnOx films to enable the realization of high-efficiency and stable PSC devices. Effects of deposition temperature and oxidant type on the properties of the ALD SnOx films were determined to be as follows: (1) lower deposited temperatures (down to 60 °C) resulted in smoother surfaces, lower gas-transmission rates(WVTR low to 1.3 × 10-2 g m-2 day-1), higher band gap and lower conductivity. (2) H2O2 yielded smoother surfaces, lower gas-transmission rates, higher SnO2 contents, higher band gap and lower conductivity. The experimental results of solar cells shown that lowering the deposition temperature, using high reactivity H2O2 as oxidant, deposing proper SnOx film thickness, increasing H2O2 dose and passivating interface between perovskite layer and SnOx can improve PSC performance. After those optimization process, a maximum power conversion efficiency (PCE) of 13.76% PSC devices with low-process temperature (below 75°C) ETL was achieved.

並列關鍵字

atomic layer deposition ； perovskite solar cells ； tin oxide ； low temperature process

參考文獻

[1] Chiang, Y. F.; Jeng, J. Y.; Lee, M. H.; Peng, S. R.; Chen, P.; Guo, T. F.; Wen, T. C.; Hsu, Y. J.; Hsu, C. M., "High voltage and efficient bilayer heterojunction solar cells based on an organic-inorganic hybrid perovskite absorber with a low-cost flexible substrate", Physical Chemistry Chemical Physics 2014, 16 (13), 6033-6040.

[2] Docampo, P.; Ball, J. M.; Darwich, M.; Eperon, G. E.; Snaith, H. J., "Efficient organometal trihalide perovskite planar-heterojunction solar cells on flexible polymer substrates", Nature Communications 2013, 4.

[3] Jung, J. W.; Williams, S. T.; Jen, A. K. Y., "Low-temperature processed high-performance flexible perovskite solar cells via rationally optimized solvent washing treatments", Rsc Advances 2014, 4 (108), 62971-62977.

[4] Qiu, L. B.; Deng, J.; Lu, X.; Yang, Z. B.; Peng, H. S., "Integrating Perovskite Solar Cells into a Flexible Fiber", Angewandte Chemie-International Edition 2014, 53 (39), 10425-10428.

[5] Wang, X. Y.; Li, Z.; Xu, W. J.; Kulkarni, S. A.; Batabyal, S. K.; Zhang, S.; Cao, A. Y.; Wong, L. H., "TiO2 nanotube arrays based flexible perovskite solar cells with transparent carbon nanotube electrode", Nano Energy 2015, 11, 728-735.