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Anion Exchange and the Quantum-Cutting Energy Threshold in Ytterbium-Doped CsPb(Cl1-xBrx)3 Perovskite Nanocrystals
摘要： Colloidal halide perovskite nanocrystals of CsPbCl3 doped with Yb3+ have demonstrated remarkably high sensitized photoluminescence quantum yields (PLQYs), approaching 200%, attributed to a picosecond quantum-cutting process in which one photon absorbed by the nanocrystal generates two photons emitted by the Yb3+ dopants. This quantum-cutting process is thought to involve a charge-neutral defect cluster within the nanocrystal's internal volume. Here, we demonstrate that Yb3+-doped CsPbCl3 nanocrystals can be converted post-synthetically to Yb3+-doped CsPb(Cl1-xBrx)3 nanocrystals without compromising the desired high PLQYs. Nanocrystal energy gaps can be tuned continuously from Eg ~ 3.06 eV (405 nm) in CsPbCl3 down to Eg ~ 2.53 eV (~490 nm) in CsPb(Cl0.25Br0.75)3 while retaining a constant PLQY above 100%. Reducing Eg further causes a rapid drop in PLQY, interpreted as reflecting an energy threshold for quantum cutting at approximately twice the energy of the Yb3+ 2F7/2 → 2F5/2 absorption threshold. These data demonstrate that very high quantum-cutting energy efficiencies can be achieved in Yb3+-doped CsPb(Cl1-xBrx)3 nanocrystals, offering the possibility to circumvent thermalization losses in conventional solar technologies. The presence of water during anion exchange is found to have a deleterious effect on the Yb3+ PLQYs but does not affect the nanocrystal shapes, morphologies, or even reduce the excitonic PLQYs of analogous undoped CsPb(Cl1-xBrx)3 nanocrystals. These results provide valuable information relevant to development and application of these unique materials for spectral-shifting solar energy conversion technologies.
关键词： ytterbium doping,quantum cutting,anion exchange,Perovskite nanocrystals
更新于2025-09-19 17:15:36
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Impact of Host Composition, Co-doping or Tri-doping on Quantum Cutting Emission of Ytterbium in Halide Perovskite Quantum Dots and Solar Cells Applications
摘要： Recently, various lanthanide ions (Ln3+) have been successfully doped into perovskite quantum dots (PQDs) and quantum-cutting emission of 2F5/2-2F7/2 for Yb3+with measurable inner efficiency more than 100 % has been discovered, applied as the luminescent converter of solar cells, which has opened a new branch for the application of PQDs. In this work, to further improve the quantum-cutting efficiency of Yb3+, the co-doping and tri-doping methods were displayed to improve the quantum cutting emission of PQDs. The Yb3+-Ln3+ (Ln=Nd, Dy, Tb, Pr, Ce) pairs doped CsPbClxBryI3-x-y PQDs were fabricated, which all displayed excitonic emissions, narrow-band emission of Ln3+ ions and quantum cutting emission of Yb3+ ions. It was interesting to observe that Yb3+-Pr3+ as well as Yb3+-Ce3+ pairs could effectively sensitize the emission of Yb3+, owing to Pr3+ and Ce3+ ions offered intermediate energy states close to the exciton transition energy of the PQDs. After host composition optimization and tri-doping investigation, overall emissions with 173% photoluminescence quantum yield (PLQY) were obtained in the Yb3+-Pr3+-Ce3+ tri-doped CsPbClBr2 PQDs. Then, the tri-doped PQDs was designed as the down-converter for the CuIn1-xGaxSe2 (CIGS) as well as the silicon solar cells, which relatively leads to enhancement of power conversion efficiency (PCE) as high as ～ 20%. The modified CIGS was further employed to charging the smart mobile phone, which could largely shorten the charging time from 180 to 150 min. This finding is of great significant for expanding the application fields of the impurity doped PQDs.
关键词： CIGS solar cell,ytterbium doping,quantum cutting,tri-doping method,Perovskite quantum dot
更新于2025-09-11 14:15:04
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Quantum Cutting Luminescent Solar Concentrators Using Ytterbium Doped Perovskite Nanocrystals
摘要： We introduce and demonstrate the concept of quantum-cutting luminescent solar concentrators (QC-LSCs) using Yb3+-doped perovskite nanocrystals. These NCs feature a photoluminescence quantum yield approaching 200% and virtually zero self-absorption loss of PL photons, defining a new upper limit of 150% for the internal optical efficiency (ηint) of LSCs that is almost independent of LSC sizes. An unoptimized 25 cm2 QC-LSC fabricated from Yb3+-doped CsPbCl3 NCs already displayed an ηint of 118.1±6.7% that is 2-fold higher than previous records using Mn2+-doped quantum dots (QDs). If using CsPbClxBr3-x NCs capable of absorbing ~7.6% of solar photons, the projected external optical efficiency (ηext) of QC-LSCs can exceed 10% for >100 cm2 devices which still remains a big challenge in the field. The advantage of QC-LSCs over conventional QD-LSCs becomes especially obvious with increasing LSC sizes, which is predicted to exhibit more than 4-fold efficiency enhancement in the case of window size (1 m2) devices.
关键词： Luminescent solar concentrators,Solar energy,Doped nanocrystals,Quantum cutting,Ytterbium doping
更新于2025-09-04 15:30:14