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Tuning hexagonal NaYbF4 nanocrystals down to sub-10 nm for enhanced photon upconversion
Nanoscale ( IF 5.8 ) Pub Date : 2017-08-21 00:00:00 , DOI: 10.1039/c7nr04877g Ruikai Shi 1, 2, 3, 4, 5 , Xincan Ling 1, 2, 3, 4, 5 , Xiaona Li 1, 2, 3, 4, 5 , Lu Zhang 1, 2, 3, 4, 5 , Min Lu 1, 2, 3, 4, 5 , Xiaoji Xie 1, 2, 3, 4, 5 , Ling Huang 1, 2, 3, 4, 5 , Wei Huang 1, 2, 3, 4, 5
Nanoscale ( IF 5.8 ) Pub Date : 2017-08-21 00:00:00 , DOI: 10.1039/c7nr04877g Ruikai Shi 1, 2, 3, 4, 5 , Xincan Ling 1, 2, 3, 4, 5 , Xiaona Li 1, 2, 3, 4, 5 , Lu Zhang 1, 2, 3, 4, 5 , Min Lu 1, 2, 3, 4, 5 , Xiaoji Xie 1, 2, 3, 4, 5 , Ling Huang 1, 2, 3, 4, 5 , Wei Huang 1, 2, 3, 4, 5
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Enhancing upconversion emission is critical for small-sized lanthanide doped upconversion nanocrystals. A promising way is increasing the doping concentration of excitation energy absorbers, the Yb3+ sensitizer. However, it is still a challenge to obtain small-sized hexagonal NaLnF4 (Ln: lanthanide) upconversion nanocrystals with a high Yb3+ concentration due to the fast growth of NaYbF4 crystals, which hinders their applications particularly in biology. We here demonstrate a highly repeatable and controllable method for tuning the size of hexagonal NaYbF4 nanocrystals, down to ∼7 nm, without the assistance of additional impurity doping. By monitoring the reaction process, we found that ultrasmall hexagonal NaYbF4 nanocrystals were formed through an in situ transformation of their cubic counterparts. We observed an enhanced upconversion emission of NaYbF4:Tm nanocrystals when compared to that of NaYbF4:Y/Tm nanocrystals with less Yb3+ doping. After coating a thin layer of a NaYF4 shell on NaYbF4:Tm nanocrystals, a ∼100 times upconversion emission enhancement with over 800 times stronger emission in the ultraviolet and blue ranges was observed. This versatile method, together with the strong upconversion emission of the as-prepared ultrasmall nanocrystals, should facilitate the future applications of upconversion nanocrystals.
中文翻译：
将六角形NaYbF 4纳米晶体调谐至10纳米以下以增强光子上转换
对于小尺寸镧系元素掺杂的上转换纳米晶体，增强上转换发射至关重要。一种有前途的方法是增加激发能吸收剂Yb 3+敏化剂的掺杂浓度。然而，由于NaYbF 4晶体的快速生长，获得具有高Yb 3+浓度的小尺寸六角形NaLnF 4（Ln：镧系元素）上转换纳米晶体仍然是一个挑战，这特别阻碍了它们在生物学中的应用。我们在这里展示了一种高度可重复且可控制的方法，用于调节六角形NaYbF 4的大小低至约7 nm的纳米晶体，无需额外的杂质掺杂。通过监测反应过程，我们发现超小型六角形NaYbF 4纳米晶体是通过它们的立方对应物的原位转变形成的。我们观察到与掺Yb 3+较少的NaYbF 4：Y / Tm纳米晶体相比，NaYbF 4：Tm纳米晶体的上转换发射增强。涂覆NaYF的薄层后4上NaYbF壳4:: Tm纳米晶体，在紫外和蓝色范围内观察到约100倍的上转换发射增强和800倍以上的强发射。这种通用的方法，与所制备的超小纳米晶体的强上转换发射一起，应有助于上转换纳米晶体的未来应用。
更新日期：2017-09-21
中文翻译：
将六角形NaYbF 4纳米晶体调谐至10纳米以下以增强光子上转换
对于小尺寸镧系元素掺杂的上转换纳米晶体，增强上转换发射至关重要。一种有前途的方法是增加激发能吸收剂Yb 3+敏化剂的掺杂浓度。然而，由于NaYbF 4晶体的快速生长，获得具有高Yb 3+浓度的小尺寸六角形NaLnF 4（Ln：镧系元素）上转换纳米晶体仍然是一个挑战，这特别阻碍了它们在生物学中的应用。我们在这里展示了一种高度可重复且可控制的方法，用于调节六角形NaYbF 4的大小低至约7 nm的纳米晶体，无需额外的杂质掺杂。通过监测反应过程，我们发现超小型六角形NaYbF 4纳米晶体是通过它们的立方对应物的原位转变形成的。我们观察到与掺Yb 3+较少的NaYbF 4：Y / Tm纳米晶体相比，NaYbF 4：Tm纳米晶体的上转换发射增强。涂覆NaYF的薄层后4上NaYbF壳4:: Tm纳米晶体，在紫外和蓝色范围内观察到约100倍的上转换发射增强和800倍以上的强发射。这种通用的方法，与所制备的超小纳米晶体的强上转换发射一起，应有助于上转换纳米晶体的未来应用。
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