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  • 學位論文

反相有機太陽能電池效率及其界面電子結構研究

Investigation of Device Performance and Interfacial Electronic Structures of Inverted Organic Solar Cells

指導教授 : 吳志毅

摘要


在本論文中,第一部分主要是碳酸銫在倒置有機太陽能電池中作為陰極緩衝層對整體元件的電性研究。利用溶液調配一定濃度的碳酸銫,並旋轉塗佈在氧化銦錫(ITO)電極上,使氧化銦錫功函數有效下降,從原本陽極角色轉變為陰極角色,形成倒置結構太陽能電池中的透明陰極。所使用的主動層有機材料是在有機太陽能電池領域中已成經典的電子施體材料『聚三己烷塞吩(P3HT)』與電子受體材料『苯基碳61丁酸甲酯(PCBM)』。將兩種有機材料在溶劑中均勻混合,再使用旋轉塗佈的方式成膜,就是太陽能電池中的主動層。由介面光譜分析可得知,經碳酸銫修飾後,氧化銦錫電極與受體材料『苯基碳61丁酸甲酯(PCBM)』之間的電子注入能障大幅減少。修飾後的氧化銦錫電極在光生電流、開路電壓等特性皆比沒有使用碳酸銫修飾的電極好,主要歸因於極薄的碳酸銫層有效降低受體材料與陰極間的電子注入能障以及碳酸銫層幾乎沒有光耗損,因此不影響元件的光電流,並完成高效率的倒置太陽能電池。 第二部分是倒置太陽能電池效率演進的探索。不同的倒置太陽能電池有不同的效率演進的成因。為了清楚了解這種新開發的倒置結構,其效率演進的成因也是探索的重點。藉由X-ray繞射儀與原子力顯微鏡,我們清楚了解微觀的有機層所發生的變化。此外,藉由介面光譜分析,電極的變化也得以清楚觀察。不同種類的量測方式讓我們可以清楚規納倒置太陽能電池效率演進的原因。

並列摘要


Excellent performance has been demonstrated of inverted organic solar cells (IOSCs) with indium tin oxide (ITO) modified by cesium carbonate. The IOSCs with modified ITO as cathodes exhibit a much longer life time as compared to organic solar cells (OSCs) with the regular structure. Using a solution-based cesium carbonate, the work function of ITO can be reduced from 4.8eV to 3.4eV to approach a relatively lower electron injection barrier. The reduction of electron injection barrier with modified ITO is also indicated by ultraviolet photoemission spectroscopy. The improvement of open circuit voltage and photo-induced current is attributed to both the reduction of electron injection barrier and the almost non-reduced light intensity. A highly efficient inverted OSC is fabricated. Evolution of device performance is also investigated. This new structure of inverted OSC leads different factors of performance evolution. To discover the aging process, several analytical methods are utilized to realize the morphology of organic layer and surface property of modified electrodes.

參考文獻


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