Browsing by Author "Jhuang, Lu-Syuan"

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Bandgap Engineering Enhances the Performance of Mixed-Cation Perovskite Materials for Indoor Photovoltaic Applications
(2019-10-01)
Wu, Ming-Ju
;
Kuo, Chien-Chen
;
Jhuang, Lu-Syuan
;
Chen, Po-Han
;
Lai, Yi-Fong
Indoor photovoltaics (IPVs) are attracting renewed interest because they can provide sustainable energy through the recycling of photon energy from household lighting facilities. Herein, the Shockley-Queisser model is used to calculate the upper limits of the power conversion efficiencies (PCEs) of perovskite solar cells (PeSCs) for two types of artificial light sources: fluorescent tubes (FTs) and white light-emitting diodes (WLEDs). An unusual zone is found in which the dependence of the PCEs on the bandgap (E-g) under illumination from the indoor lighting sources follows trends different from that under solar irradiation. In other words, IPVs exhibiting high performance under solar irradiation may not perform well under indoor lighting conditions. Furthermore, the ideal bandgap energy for harvesting photonic power from these indoor lighting sources is approximate to 1.9 eV-a value higher than that of common perovskite materials (e.g., for CH3NH3PbI3). Accordingly, Br- ions are added into the perovskite films to increase their values of E-g. A resulting PeSC featuring a wider bandgap exhibits PCEs of 25.94% and 25.12% under illumination from an FT and a WLED, respectively. Additionally, large-area (4 cm(2)) devices are prepared for which the PCE reaches approximate to 18% under indoor lighting conditions.
Bidentate chelating ligands as effective passivating materials for perovskite light-emitting diodes
(2019-04-21)
Hsiao, Ming-Chuan
;
Chien, Ping-Cheng
;
Jhuang, Lu-Syuan
;
Chen, Fang-Chung
;
交大名義發表
Herein, four pyridine-based chelating ligands, including 1,10-phenanthroline, 4,4-bipyridine, 4,7-diphenyl-1,10-phenanthroline (Bphen) and pyridine, are used as surface treatment agents for improving the electronic properties of perovskite materials. The results of the steady-state photoluminescence (PL), time resolved PL and hole-only devices made of CH3NH3PbBr3 thin films suggest that the traps are effectively passivated after post-deposition surface treatment with bidentate chelating ligands, including 1,10-phenanthroline and 4,4-bipyridine. Furthermore, the coordination capability of Bphen was suppressed which is probably due to its two additional phenyl groups, resulting in a steric hindrance effect. When compared with mono-dentate chelating pyridine, bidentate chelating ligands are more active in the current study. Finally, perovskite light-emitting diodes (PeLEDs) are fabricated and the devices exhibit a nearly doubled device efficiency after passivation with 1,10-phenanthroline. It is anticipated that the approach proposed here is a general method for improving the photonic properties of perovskite materials and the device performance of PeLEDs.