矽基堆疊型薄膜太陽能電池

Abstract

本論文之研究利用高密度電漿化學氣相沉積系統製備氫化非晶矽薄膜，發展摻雜鍺之氫化非晶矽鍺合金(a-SiGe)調變能隙漸變之矽薄膜太陽能電池，並藉由導入微晶穿遂層和高氫含量之底層光電轉換層，進一步優化堆疊型太陽能電池。由於氫化非晶矽薄膜能隙較高(1.8~1.9eV)，氫化非晶矽薄膜太陽能電池有高開路電壓的優點，但相對在太陽光譜中長波長的部分(750nm以上)無法有效吸收而造成短路電流密度較低。為了克服上述氫化非晶矽薄膜太陽能電池之缺點，我們開發非晶矽鍺合金薄膜a-SiGe (1.4~1.6eV)，使其可吸收太陽光譜中不同波段的，有效的增強光伏特元件吸收寬頻太陽光能的利用率，並且可以以各種不同能隙所製備的矽薄膜太陽能電池為基礎發展多接面堆疊型太陽能電池。本實驗室目前已經開發出各種不同能隙之單接面氫化非晶矽太陽能電池，其中單接面氫化非晶矽薄膜太陽能電池轉換效率達9.2%，導入矽鍺薄膜之單接面太陽能電池轉換效率達5.7%，且從量子效率量測結果可看出，單接面矽鍺薄膜太陽能電池在650~800nm所擁有的量子轉換效率有顯著的提升。而堆疊型太陽能電池的部分，我們目前已經開發了兩種雙層堆疊型太陽能電池，其中a-Si/a-Si以及a-Si/a-SiGe雙層堆疊型薄膜太陽能電池開路電壓分別可達到1.69以及1.46V，而a-Si/a-Si以及a-Si/a-SiGe雙層堆疊型薄膜太陽能電池轉換效率則分別為8.8%和6.3%，其中a-Si/a-SiGe之短路電流JSC到達8.45mA/cm2。未來研究的方向將致力於改善堆疊型太陽能電池各接面間的穿隧接面和各吸收層的薄膜品質，進而整合三接面堆疊型高光電轉換效率之太陽能電池。

We have fabricated silicon-based alloy tandem thin film solar cell by using high density plasma method. And optimize the tandem thin film solar by using tunneling-recombination junction and high hydrogen ratio bottom absorption layer. Due to high optical band gap of amorphous silicon thin film, a-Si thin film solar cell shows the property of high open circuit voltage. But, this feature also limit the absorption in the near infrared part of solar spectra, so the short circuit current density is much lower compared with amorphous silicon germanium alloy thin film silicon solar cell. In order to overcome the above-mentioned shortcomings, we utilize the amorphous silicon germanium alloy a-SiGe (band gap 1.4~1.6eV) to engineer the optical bandgap. The thin films with different optical bandgap could absorb the different part in solar spectra. Thus, we can effectively take advantage of the full solar spectra. And we can also develop muti-junction thin film solar cell based in the thin film solar cells. Each junctions of muti-junction solar cell have different optical bandgap, so they could absorb different part of solar spectra. Currently, we have demonstrated single junction a-Si, a-SiGe thin film solar cell with conversion efficiency achieving 9.2% and 5.7%, respectively. Compared with a-si thin film solar cell, the quantum efficiency of a-SiGe significantly increased in 650~800nm. Besides, we have also demonstrated double junctions solar cell, including a-Si/a-Si and a-Si/a-SiGe tandem solar cell. The open circuit voltage of a-Si/a-Si, a-Si/a-SiGe tandem solar cells is 1.69V, 1.46V respectively. The muti-junction we mentioned above have successful performance in open circuit voltage. Conversion efficiency of a-Si/a-Si and a-Si/a-SiGe tandem solar cell is 8.8% and 6.3% respectively. In the future, my research will focus on tunneling junction between each interface and film quality of each kind silicon based alloy to obtain the triple-junction thin film solar cell with high conversion efficiency.