Air-Stable and Environmentally Friendly Full Color-Emitting ZnSeTe/ZnSe/ZnS Quantum Dots for Display Applications

Abstract

We have developed a nontoxic method of synthesizing blue-emitting ZnSeTe/ZnSe/ZnS quantum dots (QDs), which can be employed to realize QD-based electroluminescent displays. By introducing excessive metal halides without highly toxic hydrofluoric acid, we achieved a very high photoluminescence quantum yield reaching 94%. Furthermore, for the first time, air-stable ZnSeTe/ZnSe/ZnS QDs were demonstrated by employing simple surface ligand exchange performed both in solution and solid states. Various spectroscopic studies revealed that initial carboxylate ligands could be very effectively replaced by our simple ligand exchange at room temperature. In addition, we significantly broadened the spectral range of QDs by increasing the Te ratio of the core; therefore, green-and red-emitting ZnSeTe/ZnSe/ZnS QDs were demonstrated. The air-stable Zn-based QDs with full color emission developed in our study can be used as superior emitters in displays.

Transparent p–n Junction in Cu2O/ZnS/ZnO Core–Shell Nanoarrays via In Situ Sulfuration for Enhanced Photovoltaic Stability

“…15−18 Further, the peaks at 161.18 and 162.32 eV are from S 2+ ions (Figure S1c), and the peak at 168.13 eV is from the surface-exposed S atoms. 42,43 Combined with Figure S1a, these results indicate the successful in situ sulfuration process and formation of ZnS shell. 42−45 The peaks at 932.35 and 952.18 eV are ascribed to Cu + from Cu 2 O film (Figure S1d).…”

“…40,41 In particular, in addition to exhibiting adjustable potential, modification of the ZnS layer can alleviate the Fermi level gradient for improving carrier transportation and demonstrate higher quantum yield (QY) and wider bandgap, which can provide an effective carrier injection while sustaining good transparency. 42,43 Kim et al introduced ZnS for improving the transparent photoelectric property of ZnO/CuI. 44 Compared with other transition layer modifications, in situ sulfuration exhibits unique advantages.…”

“…However, the current progress of transparent photovoltaic device has not been successful to meet the actual standards and requirements, because balancing carrier concentration and mobility has always been a bottleneck for transparent photoelectricity. − Hence, several efficient methods are being reported as a consequence of continuous research, , including surface modification and interface quantum dot modification or doping. Among these reported methods, transition layer modification with potential regulation and carrier injection has attracted considerable attention. , In particular, in addition to exhibiting adjustable potential, modification of the ZnS layer can alleviate the Fermi level gradient for improving carrier transportation and demonstrate higher quantum yield (QY) and wider bandgap, which can provide an effective carrier injection while sustaining good transparency. , Kim et al introduced ZnS for improving the transparent photoelectric property of ZnO/CuI . Compared with other transition layer modifications, in situ sulfuration exhibits unique advantages .…”

CuI/BaSnO3 Quantum Dot/ZnSnO3 Perovskite-based Transparent p–n Junction for Photovoltaic Enhancement

“…53 Additionally, the small size of perovskite QD optimizes interface contact and further improves the formed p−n junction. 54,55 Herein, CuI/BaSnO 3 QD/ZnSnO 3 perovskite-based transparent p−n junction was prepared with homologous perovskite BaSnO 3 QD's transition layer using a hybrid approach involving sol−gel, freeze-drying, annealing, and sputtering. The CuI/BaSnO 3 QD/ZnSnO 3 perovskite-based transparent p−n junction exhibits a high transmittance of ∼85% and a photovoltaic enhancement of ∼2.6 × 10 3 folds compared to CuI/ZnSnO 3 (PCE of ∼1.13%).…”

“…In the case of homologous BaSnO 3 QD, , which possess high QY, high carrier mobility, and an appropriate potential structure, their similar perovskite crystal structure to ZnSnO 3 provides a more relaxed potential transitions and high-quality interface lattice matching, thereby improving carrier efficiency. − For example, Sun et al used BaSnO 3 nanoparticles as an electronic transport layer to reduce leakage current, enhance interface extraction, and decrease charge transfer resistance in perovskite solar cells . Additionally, the small size of perovskite QD optimizes interface contact and further improves the formed p–n junction. , …”