有機/無機混合型串疊式太陽能電池

Abstract

我們提出了一種雙接面的有機/無機混合型串疊式太陽能電池，其中的組成上下電池分別為有機太陽能電池(P3HT/PC60BM)與有機/無機混合型太陽能電池(PEDOT:PSS/Crystalline-Si)，因著混合型元件結構上的特點，我們可以直接將有機材料旋塗在無機材料矽基板上，並透過熱蒸鍍的方式鍍上元件的電極即完成了整個元件的製作，這樣簡單的溶液製程能快速製作元件且花費的成本相當低，如果有機/無機混合型串疊式的太陽能電池設計適當，我們預期將會有較高的開路電壓與轉換效率，非常有機會成為下一世代低成本且高效率的太陽能電池。 我們利用模擬軟體來瞭解有機/無機混合型串疊式太陽能電池的特性，首先建構了上下子電池的模擬模型，並透過實際的實驗數據來檢視上下子電池模擬結果是否正確，接下來在兩個子電池之中置入複合層進行有機/無機混合型串疊式太陽能電池的模擬，我們從中發現複合層在串疊式元件裡扮演了極重要的角色，對於串疊式元件的特性與效率有很大的影響，在我們初步的模擬結果中顯示，有機/無機混合型串疊式太陽能電池將會有以下的特性：開路電壓VOC為0.949 (V)，短路電流JSC為6.794 (mA/cm2)，填充因子FF為57.743 %，能量轉換效率PCE為3.723 %。 我們也設計了可行的結構與製程來製作有機/無機混合型串疊式太陽能電池，同時發現串疊式太陽能電池的中間層對於整體元件的特性有很大的影響，而且可以使用蒸鍍製程或者是溶液製程來製作，但是目前真實元件的特性和轉換效率還離模擬結果有一段差距，現階段蒸鍍製程的結果：開路電壓VOC為0.745 (V)，短路電流JSC為3.895 (mA/cm2)，填充因子FF為40.561 %，能量轉換效率PCE為1.177 %，溶液製程的結果：開路電壓VOC為0.772 (V)，短路電流JSC為3.132 (mA/cm2)，填充因子FF為23.957 %，能量轉換效率PCE為0.58 %，在此論文中我們會針對目前所遭遇到的問題與挑戰做深入的討論，包含薄膜物理、中間層材料選擇和元件的製程設計等。

We propose a series-connected hybrid tandem solar cell which consists of an organic solar cell (P3HT/PC60BM) as the top cell and an organic/crystalline silicon hybrid solar cell (PEDOT:PSS/c-Si nanowires) as the bottom cell. Based on the device structure, the organic materials can be directly spun-cast onto the inorganic silicon substrate with thermally evaporated metal contacts, making solution-based processes possible for rapid and low-cost production. With a proper design, the hybrid tandem device architecture can achieve a high open-circuit voltage (VOC) and power conversion efficiency (PCE), offering a promising approach for next-generation, low-cost and high-efficiency photovoltaics. We established a device simulation model to investigate the photovoltaic characteristics of the proposed hybrid tandem solar cells by combining the organic and silicon-based hybrid solar cells with a hypothetic recombination layer. First, the model of single junction solar cells is fitted to the current-voltage curve of fabricated devices. Next, we investigate the properties of the recombination layer between the sub-cells and observe strong correlations with the photovoltaic performance of tandem cells. In our preliminary model, we have realized a tandem cell with an open-circuit voltage (VOC), short-circuit current (JSC), fill-factor (FF) and power conversion efficiency (PCE) of 0.949 (V), 6.794 (mA/cm2), 57.743 % and 3.724 %, respectively. We also designed the structures and processes for the sub-cells and hybrid tandem solar cells fabrication. The intermediate layer between the sub-cells strongly affects the photovoltaic performance of the tandem cells and can be presented with evaporation or solution process. Currently, the characteristics of real hybrid tandem solar cells remain significantly lower than the simulation results. For evaporation process, we obtained the tandem cell with an open-circuit voltage (VOC), short-circuit current (JSC), fill-factor (FF) and power conversion efficiency (PCE) of 0.745 (V), 3.895 (mA/cm2), 40.561 % and 1.177 %, respectively. For solution process, we obtained the tandem cell with an open-circuit voltage (VOC), short-circuit current (JSC), fill-factor (FF) and power conversion efficiency (PCE) of 0.772 (V), 3.132 (mA/cm2), 23.957 % and 0.58 %, respectively. A number of challenging issues, including interface physics、recombination layer and device design will be discussed in this thesis.