矽基太陽能電池熱處理分析及製程技術比較

Abstract

現今太陽能電池的種類很多，不過市場上主要還是以矽基為主，因此在本實驗中以矽基太陽能電池來探討。目前非晶矽太陽能電池中所使用的透明導電層各有不同，為了瞭解其差異，在實驗中使用FTO玻璃和ITO玻璃來當基板，完成太陽能電池製作後進行熱處理，使用不同條件的快速退火溫度，然後觀察其各種特徵參數的改變，如開路電壓、短路電流、填充因子、轉換效率等。而從實驗結果來看，可以發現FTO玻璃可以承受的溫度較高，各種特徵參數不會隨升溫而迅速變差，並從串聯電阻和分流電阻來探討其原因。 另一方面，高效率的異質接面太陽能電池(HIT)也是實驗探討的內容之一，提高效率即可降低其生產成本，故從製程方面的參數改變，如使用的基板種類、基板厚度、背電場的有無等等，來探討其最佳化的參數設計，以提高其效率。從實驗中可發現，有製作背電場和使用IC等級的晶圓，的確可以達到較好的效率，期望未來可以改良製程條件和參數等，達到最佳化的條件，進一步提高異質接面太陽能電池的效率。

The state-of-the-art solar cells have many types, but silicon based type is the mainstream for the market. Therefore, we will discuss the Si-based solar cell in this study. Several kinds of transparent conductive layer (TCO) are suited for amorphous Si solar cell. We used the FTO glass and ITO glass to investigate performance, as well as the heat treatment with different annealing condition will be performed. The devices parameters are extracted, such as open circuit voltage (VOC), short circuit current (ISC), fill factor (F.F), conversion efficiency (η). After the thermal annealing of a-Si:H thin film solar cell on FTO glass, the efficiency has slight enhanced until 250 C, and degraded at 300 C. The phase transition of a-Si:H is occurred for 300C annealing and makes Rsh decreasing dramatically. We also discussed the results from the series resistance (Rs) and shunt resistance (Rsh). On the other hand, high-efficiency Heterojunction with Intrinsic Thin Layer (HIT) solar cell also is fabricated and studied in this work. The higher efficiency means the cost down for solar cell market. Therefore, we will optimize the process parameters, such as the substrate types, substrate thickness, back surface electric field, etc. The efficiency is improved with back surface electric field (BSF) with IC grade wafer. We expect the process and structure optimization with high efficiency solar cells for next generation.