臨場分析技術應用於鈣鈦礦太陽能電池衰退機制之探討

In-Situ Analytical Techniques for Investigating the Degradation Mechanism of Perovskite Solar Cell

陳柏安(Bo-An Chen)

指導教授 ： 陳浩銘

國立臺灣大學/理學院/化學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602725

摘要

近年來鈣鈦礦太陽能電池在科學研究上受到極大的關注，主要的原因是由於其光電轉換效率爆炸性的發展在僅僅七年內從3.81% 提升至22.1%。但相較於已商業化的矽基與薄膜型太陽能電池，鈣鈦礦太陽能電池的長時間穩定性為影響其實際商業化應用的最主要的原因。直至現今，已有數個研究團隊致力於研究其衰退機制並改善鈣鈦礦太陽能電池的穩定性。
有別於其他研究團隊的分析方式，本研究將發展兩種臨場(in-situ)技術搭載X-ray 粉體繞射分析儀與 X-ray 吸收光譜術來研究鈣鈦礦太陽能電池在不同工作環境中其晶體結構與化學價態的即時變化，藉此探討其穩定性衰退主因。更進一步的，本研究在臨場 X-ray 粉體繞射儀上搭載電性量測單元與模擬太陽光照射來觀察鈣鈦礦太陽能電池的晶體結構與其效率變化之間的關係，更可提出造成其效率衰退的直接證據。研究結果顯示當太陽能電池在低濕度的工作環境時，其光電轉換效率降低分為三個步驟進行，且晶體結構逐漸地轉變為PbI2，然而當在高濕度的環境下執行量測時，發現光電轉換效率在僅僅數分鐘內大幅下降，其所對應的晶體結構快速轉變為PbI2，而最終將由PbI2更進一步的轉變為PbIOH。此為首次完整探討CH3NH3PbI3鈣鈦礦太陽能電池於模擬太陽光照射工作的情況下，同步藉由X-ray 粉末繞射分析儀分析其衰退機制，並首次於衰退機制中發現PbIOH的生成。

關鍵字

鈣鈦礦 ； 太陽能電池 ； 穩定性 ； 臨場

並列摘要

Perovskite solar cells nowadays attract extensive attentions in scientific research because of its explosive improvement of power conversion efficiency from 3.81 ~ 22.1% merely in seven years. However, long term stability of perovskite solar cell is still a critical problem for practical application. Toward this end, there have been several research groups devoted to investigate the stability and degradation mechanism of perovskite solar cell.
Herein, we developed two kinds of in situ techniques including X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XAS) to investigate the change of the crystal structure and chemical state of CH3NH3PbI3. Furthermore, the in situ XRD system was equipped with source meter and real-time solar irradiation to observe correlation between the crystallographic structure of perovskite and the evolution of solar cell performance. We observed when the solar cell worked under low humidity condition, the power conversion efficiency (PCE) decreased in three steps and the crystallographic structure of perovskite gradually transformed into PbI2. However, when we conducted the measurements under high humidity condition, the PCE dropped dramatically in just merely few minutes and the perovskite transformed into PbI2 immediately following convert to PbIOH in the end. This is the first time we found the new phase PbIOH generated and investigated the perovskite solar cell degradation mechanism under real-time solar irradiation combined with X-ray diffraction analysis.

並列關鍵字

perovskite ； solar cell ； stability ； in-situ

參考文獻

[29] 姚潔宜，X光的奇妙世界，國家奈米元件實驗室

[38] Z. Xiao, C. Bi, Y. Shao, Q. Dong, Q. Wang, Y. Yuan, C. Wang, Y. Gao, J. Huang, Energ Environ. Sci. 2014, 7, 2619-2623.

[43] H. J. Snaith, A. Abate, J. M. Ball, G. E. Eperon, T. Leijtens, N. K. Noel, S. D. Stranks, J. T.-W. Wang, K. Wojciechowski, W. Zhang, J. Phys. Chem. Lett. 2014, 5, 1511-1515.

[40] Z. Xiao, Y. Yuan, Y. Shao, Q. Wang, Q. Dong, C. Bi, P. Sharma, A. Gruverman, J. Huang, Nat. Mater. 2015, 14, 193-198.

[41] Y. Shao, Z. Xiao, C. Bi, Y. Yuan, J. Huang, Nat. Commun. 2014, 5.