太陽能電池之外部光捕捉運用頻譜轉換高分子與漫反射器

Abstract

近年來，許多研究顯示外部光補捉(External light trapping)有很大的潛力可取代傳統型內部光補捉(Internal light trapping)設計。目前的光捕捉機制可分為外部與內部的設計，傳統型內部光補捉雖然可以有效的幫助電池效率的提升，但卻無法單獨的控制其電子與光學的特性；因此在內部的光補捉下，有好的光學結構，卻不能保證有好的電子傳輸特性。而外部光補捉的優點在於可以將太陽能電池之電子與光學特性分開設計。在本文實驗中，我們利用外部的漫射反射器加上螢光粉的頻譜下轉移(Luminescent down shifting)特性製作出低成本的外部光補捉設計結構，並以非晶矽薄膜太陽能電池作為測試電池。實驗結果顯示，電池的電流密度提升了約110%。除此之外，由於光補捉為外部附加的設計，並不會影響到電池本身的結構，因此可以應用於多種薄膜太陽能電池，並且有效的提升其效率與電流密度。

External light trapping has been proposed as a choice to replace internal light trapping. To date, the mechanisms of light trapping can be classified into two parts, external and internal. Although the design of internal light trapping can enhance the cell efficiency and JSC, it may affect the electrical diode characteristic of solar cells and structure. On the other hand, the advantage of external light trapping is that the electrical and optical characteristics can be designed separately. Additionally, the degree of enhancement by external light trapping can be much higher than what is achievable by internal ones. In this paper, we present a simple approach for enhancing the efficiency and JSC of amorphous silicon solar cell by diffuse trench reflectors with luminescent down shifting polymer. A >110 % enhancement of the JSC can be observed with proper designs and configurations. The proposed external light trap can be applied to nearly all thin-film solar cell technologies since the external optical components do not affect the electrical diode characteristic of the solar cells. The efficient external light trap is attributed to the high reflectance of the disuse mirror and its wide-angle diffractions, optical confinement due to the trench reflector, and the additional short-wavelength spectral enhancement by the luminescent down shifting mechanism.