Browsing by Author "Li, Feng"

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Diammonium and Monoammonium Mixed-Organic-Cation Perovskites for High Performance Solar Cells with Improved Stability
(2017-09-20)
Lu, Jianfeng
;
Jiang, Liangcong
;
Li, Wei
;
Li, Feng
;
Pai, Narendra K.
Remarkable power conversion efficiencies (PCE) of metal-halide perovskite solar cells (PSCs) are overshadowed by concerns about their ultimate stability, which is arguably the prime obstacle to commercialization of this promising technology. Herein, the problem is addressed by introducing ethane-1,2-diammonium (+NH3(CH2)(2)NH3+, EDA(2+)) cations into the methyl ammonium (CH3NH3+, MA(+)) lead iodide perovskite, which enables, inter alia, systematic tuning of the morphology, electronic structure, light absorption, and photoluminescence properties of the perovskite films. Incorporation of < 5 mol% EDA(2+) induces strain in the perovskite crystal structure with no new phase formed. With 0.8 mol% EDA(2+), PCE of the MAPbI(3)-based PSCs (aperture of 0.16 cm(2)) improves from 16.7% +/- 0.6% to 17.9% +/- 0.4% under 1 sun irradiation, and fabrication of larger area devices (aperture 1.04 cm(2)) with a certified PCE of 15.2% +/- 0.5% is demonstrated. Most importantly, EDA(2+)/MA(+)-based solar cells retain 75% of the initial performance after 72 h of continuous operation at 50% relative humidity and 50 degrees C under 1 sun illumination, whereas the MAPbI(3) devices degrade by approximately 90% within only 15 h. This substantial improvement in stability is attributed to the steric and coulombic interactions of embedded EDA(2+) in the perovskite structure.
Research on a Novel GaN-Based Converted Mini-LED Backlight Module via a Spectrum-Decouple System
(2020-01-01)
Huang, Che-Hsuan
;
Chang, Shu Hsiu
;
Liaw, Been-Yu
;
Liu, Cheng-Yi
;
Chou, Chia-Yueh
Owing to the development of modern display technology, micro- and mini-light-emitting diodes (LEDs) have affected technological advancements in the display industry. The structure of mini-LEDs is completely different than that of traditional LED backlights because the former employs a display technology with an LED array structure, optical resonant cavity, and color conversion layer. Display backlight technology encounters difficulty in achieving a truly effective energy-loss mechanism when designing or measuring mini-LED performance. The present study proposes three major mini-LED energy loss mechanisms: cross-talk, resonant, and quantum conversion losses. Herein, the spectrum was obtained through the integrating sphere system, and the calculation mechanism was formed by the down-conversion theorem as the decoupling principle, which successfully calculated the independent energy-loss efficiency of each mechanism and effectively deduced the brightness and color saturation performance of this design combination.