本質薄膜之異質接面太陽能電池

Abstract

近年來，許多研究顯示利用不同的材料與合成方法結合機制以提升轉換太陽光之效率並應用於太陽能電池上，其中轉換太陽光效率機制又分為上轉換及下轉換，在本文實驗中，利用頻譜下轉移(Luminescent down shifting)特性製作出低成本的異質接面，利用具下轉換機制之螢光粉末將未充分利用的高能量光子轉換成太陽能電池光譜響應較佳之低能光子。此方法克服電池在短波段的低頻譜響應與電池表面複合問題。本質薄膜之異質接面Heterojunction Intrinsic with Thin layer (HIT) 太陽能電池具有高效率、製程溫度<260°C、低成本、元件結構高度對稱，在一定程度上減少了電的熱應力與機械應力等等的優點。本實驗利用在HIT太陽能電池的頂部噴塗薄的螢光粉層，一方面由於表面形貌造成全波段反射率下降外，另一方面也由於下轉換效應，使得紫外光能有效被利用，而不受到表面缺陷的影響，造成其轉換效率低落。實驗結果顯示，以600nm附近的波長去激發螢光粉，可獲得波段300~450 nm區域的光放射，所以元件的吸光度增加，其中外部量子效率（EQE）對於非晶矽太陽能電池也明顯上升。結果，短路電流增加11〜17％，進而增加了轉換效率14〜16％。這項研究顯示了螢光粉未來可能成為下一代太陽能電池的潛力。

In this work, Heterojunction Intrinsic Thin-layer (HIT) solar cell is incorporated with the luminescent down-shifting (LDS) mechanism for the incident spectrum. LDS layers contain the conversion from underutilized high-energy photon to lower energy photon where the spectral response of the solar cell is more efficient. The method conquers the poor response and surface recombination effect of solar cell at short wavelength. The HIT solar cell is highly efficient, low temperature < 260°C, low cost, and highly symmetrical device. A thin phosphor layer is spray coated on the top of HIT solar cell for the luminescent down-shifting of high energy photons and thus enhanced absorbance for the device around =600nm is reported where the external quantum efficiency (EQE) is the highest for amorphous silicon solar cells. As a result, the Jsc increased 11~17%, then increasing the η 14~16%. Finally, phosphor can apply in any kind of solar cells with increasing Jsc and η. This study shows the phosphors’ potential for becoming next generation solar cell in the future.