Sr_3Al_2O_6∶Tb~(3+),Yb~(3+)荧光粉的近红外量子剪裁效应

硅材料带隙与太阳光子光谱的失配导致了比较严重的光子损失,大大降低了硅太阳能电池的效率。为了减少入射光子的损失,可以利用具有近红外量子剪裁效应的光谱转换材料来提高硅太阳能电池的效率。本研究采用溶胶凝胶法制备了Sr_3Al_2O_6∶Tb~(3+),Yb~(3+)荧光粉,并研究了其近红外量子剪裁效应。实验结果表明:在320 nm的紫外光激发下,Sr_3Al_2O_6∶Tb~(3+),Yb~(3+)荧光粉发射出Tb~(3+):5D4→~7F_j的可见光;另外,由于Tb~(3+)、Yb~(3+)离子之间的合作能量传递,得到了Yb~(3+):~7F_(5/2)→7F7/2的近红外发光。荧光寿命衰减证明Tb~(3+)到Yb~(3+)之间的确存在合作能量传递,而且存在量子剪裁效应,其中,能量传递效率为35.9%,量子剪裁效率为135.9%。由于Yb~(3+)的发射光谱与硅太阳能电池的吸收匹配,Sr_3Al_2O_6∶Tb~(3+),Yb~(3+)荧光粉有可能作为潜在的光谱转换材料应用于硅太阳能电池以提高其光电转换效率。

Near-infrared Quantum Cutting of Sr3Al2O6∶Tb3+,Yb3+ Phosphors

The mismatch between band gap of silicon cell and solar spectra results in serious loss of energy, which greatly reduces the efficiency of silicon solar cell.In order to decrease the loss of incident photons like ultraviolet (UV) photons, the photoluminescence materials with near-infrared (NIR) quantum cutting (QC) effect can be used as spectra transformation materials to enhance the efficiency of silicon solar cells.As a novel kind of efficient NIR quantum cutting material, Sr3Al2O6∶Tb3+,Yb3+ phosphors promising for silicon solar cells were successfully prepared using sol-gel method.The luminescence properties of Sr3Al2O6∶Tb3+,Yb3+ were investigated using photoluminescence (PL) spectra and decay lifetime curves.The results show that the phosphors can emit visible light of Tb3+:5D4→7Fj under the excitation of 320 nm, while NIR light is emitted by Yb3+:7F5/2→7F7/2 through cooperative energy transfer from one Tb3+ ion to two Yb3+ ions.Decay lifetimes of Tb3+ and quantum efficiency (QE) were studied for Sr3Al2O6:Tb3+ and Sr3Al2O6∶Tb3+,Yb3+.The results show that there is effective cooperative energy transfer from Tb3+ to Yb3+, in which maximum energy transfer efficiency (ETE) and the corresponding quantum efficiency are estimated to be 35.9% and 135.9%, respectively.The results demonstrate that Sr3Al2O6∶Tb3+,Yb3+ phosphors are promising candidate for improving the efficiency of silicon based solar cell by means of down-conversion.