摘要
采用改进的坩埚下降法成功地生长了Tm／Yb共掺氟化钇锂单晶．该单晶体具有每吸收一个蓝色光子并能发射出2个1000nm近红外光子的下转换发光效应．测定了样品的激发光谱、发射光谱和荧光衰减曲线．在465nm蓝光激发下观察到由Yb3＋：0F5，2→2F7／2能级跃迁所致的960~1050nm波段的发射带，此发光带源于Tm3＋对yb3＋离子的能量下转换过程．应用Inokuti—Hirayama模型，研究了晶体的能量转换过程，结果表明Tm3＋向Yb3＋的能量传递是一个电偶极子相互作用机制过程．当Tm3＋与Yb3＋离子的掺杂浓度为0．49mol％与5．99mol％时，单晶的量子剪裁效率达到最大值167．5％．
Downconversion （DC） with emission of two near-infrared photons about 1000 nm for each blue photon absorbed was obtained in thulium （Tm3＋） and ytterbium （Yb3＋） codoped yt- trium lithium fluoride （LiYF4） single crystals grown by an improved Bridgman method. The luminescent properties of the crystals were measured through photoluminescence excitation, emission spectra and decay curves. Luminescence between 960 and 1050 nm from yb3＋： 2Fs/2--＋2FT/2 transition, which was originated from the DC from Tm3＋ ions to Yb3＋ ions, was observed under the excitation of blue photon at 465 nm. Moreover, the energy transfer processes were studied based on the Inokuti-Hirayama model, and the results indicated that the energy transfer from Tm3＋ to Yb3＋ was an electric dipole-dipole interaction. The max- imum quantum cutting efficiency approached with 0.49mo1% Tm3＋ and 5.99mo1% Yb3＋. increasing the energy efficiency of crystalline energy part of the solar spectrum. up to 167.5% in LiYF4 single crystal codoped Application of this crystal has prospects for Si solar cells by photon doubling of the high
