太阳电池用Bragg反射器的设计及研究

Design and research of Bragg reflector for solar cells

为提高GaAs/Ge太阳电池对光的吸收 ,我们对Ge衬底Bragg反射器进行了研究。根据GaAs材料对太阳光谱的吸收特点 ,通过转移矩阵的方法 ,对中心波长为 85 0nm的AlxGa1-xAs系材料Bragg反射器进行了光反射的理论计算和设计。依据理论设计 ,利用低压金属有机化合物化学气相沉积 (LP MOCVD)技术在Ge衬底上外延生长中心波长为 85 0nm的Bragg结构 ,测得的反射谱与理论设计相吻合 ,X Ray双晶衍射测得的Bragg周期厚度为 1 1 0nm。制作出具有埋层Bragg结构的GaAs/Ge太阳电池。对整个电池吸收系数的测试结果表明具有埋层Bragg结构的太阳电池的吸收系数低于无Bragg结构的电池。AM 1 .5光谱下电池I V曲线测试结果为 :Voc=1 .0 33V ,Jsc=2 6 .0 4mA/cm2 ,FF =82 .5 2 % ,η =2 2 .2 % 。

WT5BZ]Al xGa 1-x As Bragg reflector was designed and researched in order to increase the absorbability of photon near the GaAs band gap. According to the character of absorption of solar spectrum, the theoretical calculation and design of Al xGa 1-x As Bragg reflector with the peak wavelength of 850 nm was made by means of moving the matrix. The Bragg reflector with the peak wavelength of 850 nm was grown epitaxially on the Ge substrate by the LP MOCVD technology and the reflection spectra was measured to be very closely to the theoretical curves. The period thickness of Bragg was measured to be 110 nm by means of X Ray diffraction rocking. The GaAs/Ge solar cell with buried layer Bragg reflector was fabricated. The test results of the whole cell show that the absorption coefficient of solar cell with buried layer Bragg reflectors is lower than that without Bragg. The best cell with the size of 2×2 cm 2 was measured at one sun AM 1.5 and the results was as the following: V oc =1.03 V, J sc =26.04 mA/cm 2, FF=82.52% and η=22.2%. The performance of GaAs/Ge solar cell was initially studied.