Browsing by Author "Wu, Congcong"

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    High efficiency planar-type perovskite solar cells with negligible hysteresis using EDTA-complexed SnO2
    Yang, Dong; Yang, Ruixia; Wang, Kai; Wu, Congcong; Zhu, Xuejie; Feng, Jiangshan; Ren, Xiaodong; Fang, Guojia; Priya, Shashank; Liu, Shengzhong (Frank) (Springer Nature, 2018-08-13)
    Even though the mesoporous-type perovskite solar cell (PSC) is known for high efficiency, its planar-type counterpart exhibits lower efficiency and hysteretic response. Herein, we report success in suppressing hysteresis and record efficiency for planar-type devices using EDTA-complexed tin oxide (SnO2) electron-transport layer. The Fermi level of EDTA-complexed SnO2 is better matched with the conduction band of perovskite, leading to high open-circuit voltage. Its electron mobility is about three times larger than that of the SnO2. The record power conversion efficiency of planar-type PSCs with EDTA-complexed SnO2 increases to 21.60% (certified at 21.52% by Newport) with negligible hysteresis. Meanwhile, the low-temperature processed EDTA-complexed SnO2 enables 18.28% efficiency for a flexible device. Moreover, the unsealed PSCs with EDTA-complexed SnO2 degrade only by 8% exposed in an ambient atmosphere after 2880 h, and only by 14% after 120 h under irradiation at 100 mW cm−2.
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    Ultrahigh Durability Perovskite Solar Cells
    Wu, Congcong; Wang, Kai; Feng, Xu; Jiang, Yuanyuan; Yang, Dong; Hou, Yuchen; Yan, Yongke; Sanghadasa, Mohan; Priya, Shashank (American Chemical Society, 2019-01-29)
    Unprecedented conversion efficiency has been demonstrated for perovskite solar cells (PSCs), however, their stability and reliability continue to be challenge. Here, an effective and practical method is demonstrated to overcome the device stability issues in PSCs. A CF4 plasma treatment method is developed that results in the formation of a robust C–Fx layer covering the PSC device, thereby, imparting protection during the operation of solar cell. PSCs exposed to fluorination process showed excellent stability against water, light, and oxygen, displaying relatively no noticeable degradation after being dipped into water for considerable time period. The fluorination process did not have any impact on the morphology and electrical property of the top Spiro-OMeTAD layer, resulting in a conversion efficiency of 18.7%, which is identical to that of the pristine PSC. Under the continuous Xe lamp (AM 1.5G, 1 sun) illumination in ambient air for 100 h, the fluorinated PSCs demonstrated 70% of initial conversion efficiency, which is 4000% higher than that of the pristine PSC devices. We believe this breakthrough will have significant impact on the transition of PSCs into real world applications.