Low‐power photon upconversion (UC) based on sensitized triplet–triplet annihilation (sTTA) is considered as the most promising upward wavelength‐shifting technique to enhance the light‐harvesting capability of solar devices. Colloidal nanocrystals (NCs) with conjugated organic ligands have been recently proposed to extend the limited light‐harvesting capability of molecular absorbers. Key to their functioning is efficient energy transfer (ET) from the NC to the triplet state of the ligands that sensitize free annihilator moieties responsible for the upconverted luminescence. The ET efficiency is typically limited by parasitic processes, above all nonradiative hole‐transfer to the ligand highest occupied molecular orbital (HOMO). Here, a new exciton‐manipulation approach is demonstrated that enables loss‐free ET by electronically doping CdSe NCs with gold impurities that introduce a hole‐accepting intragap state above the HOMO energy of 9‐anthracene acid ligands. Upon photoexcitation, the NC photoholes are rapidly routed to the Au‐level, producing a long‐lived bound exciton in perfect resonance with the ligand triplet. This hinders hole‐transfer leading to ≈100% efficient ET that translates into an upconversion quantum yield as high as ≈12% (≈24% in the normalized definition), which is the highest performance for NC‐based upconverters based on sTTA to date and approaches the record efficiency of optimized organic systems.

中文翻译：

---

通过电子掺杂纳米晶体中的超快空穴转移，通过混合三重态敏化剂实现了高光子上转换效率。

基于三重态三重态三重态an灭（sTTA）的低功率光子上转换（UC）被认为是增强太阳能器件的光收集能力的最有希望的向上波长移位技术。最近有人提出了具有共轭有机配体的胶体纳米晶体（NCs），以扩展分子吸收剂有限的光收集能力。其功能的关键是从NC到配体的三重态的有效能量转移（ET），该态使对上转换发光负责的游离an灭剂部分敏感。ET效率通常受寄生过程限制，首先是非辐射空穴转移至配体最高占据分子轨道（HOMO）。这里，演示了一种新的激子操纵方法，该方法通过用金杂质电子掺杂CdSe NCs来实现无损ET，金杂质在9-蒽酸配体的HOMO能级以上引入空穴接受能隙状态。光激发后，NC光孔被快速路由至Au级，从而产生长寿命的结合激子，与配体三重态完美共振。这阻碍了空穴转移，导致效率高达≈100％的ET，转化效率高达≈12％（归一化定义为≈24％），这是迄今为止基于sTTA的基于NC的上变频器的最高性能并达到优化有机系统的创纪录效率。NC光孔被快速路由至Au级，产生与配体三重态完美共振的长寿命激子。这阻碍了空穴转移，从而导致≈100％的高效ET，转化为高达≈12％的上转换量子产率（在归一化定义中约为24％），这是迄今为止基于sTTA的基于NC的上变频器的最高性能并达到优化有机系统的创纪录效率。NC光孔被快速路由至Au级，产生与配体三重态完美共振的长寿命激子。这阻碍了空穴转移，从而导致≈100％的高效ET，转化为高达≈12％的上转换量子产率（在归一化定义中约为24％），这是迄今为止基于sTTA的基于NC的上变频器的最高性能并达到优化有机系统的创纪录效率。