Browsing by Author "Lee, Jiun-Haw"

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Optimizing hole-injection in organic electroluminescent devices by modifying CuPc/NPB interface
(2011-09-01)
Jiang, Meng-Dan
;
Lee, Pei-Yu
;
Chiu, Tien-Lung
;
Lin, Hong-Cheu
;
Lee, Jiun-Haw
This investigation discusses the performance of an organic light-emitting device (OLED) with ultraviolet (UV) illuminated and remote pulsed Ar plasma (RPAP), treated copper phthalcyanine (CuPc) thin film on an indium tin oxide anode as the hole-blocking layer. UV treatment increased the driving voltage, the current efficiency decreased at the same time due to the poor sticking probability of NPB on the CuPc surface. By contrast, the driving voltage reduction and current efficiency enhancement were achieved at the same time for the OLED with the RPAP treated CuPc. Besides this, in such device, the thickness of CuPc affects seldom the current density-voltage-luminance characteristics. The surface characteristics of these processed CuPc thin films were investigated by using atomic force microscope, contact angle and X-ray photoelectron spectroscopy measurements, which showed the CuPc/, N,N'-bis-(1-naphthyl)-N,N'-dipheny1-1,1'-bipheny1-4,4'-diamine (NPB) interface was crucial to not only the interface energy barrier, but also the following NPB growth, mode. (C) 2011 Elsevier B.V. All rights reserved.
Smart Transflective Display Integrated with PDLC and OPV-embedded-OLED
(2009-01-01)
Lee, Jiun-Haw
;
Chiu, Tien-Lung
;
Chuang, Kai-Hsiang
;
Lin, Yi-Hsin
;
Wu, Shin-Tson
We demonstrated a hybrid transfective device by vertically integrating a PDLC and an OLED with OPV as the reflective and transmissive mode, respectively. Such an OPV in an OLED absorbs light and converts into electrical power, which reduces the power consumption and also acts as the integrated sensor.
Suppression of surface recombination in CuInSe2 (CIS) thin films via Trioctylphosphine Sulfide (TOP:S) surface passivation
(2016-03)
Luo, Shi
;
Eisler, Carissa
;
Wong, Tsun-Hsin
;
Xiao, Hai
;
Lin, Chuan-En
CuInSe2 (CIS) solar cells are promising candidates for thin film photovoltaic applications, one key limitation in their performance is surface recombination in these thin films. We demonstrate that passivating CIS films with Trioctylphosphine Sulfide (TOP:S) solution increases photoluminescence (PL) intensity by a factor of similar to 30, which suggests that this passivation significantly reduces surface recombination. X-ray photoelectron spectroscopy (XPS) reveals that TOP:S forms both -S and -P bonds on the CIS film surface, which leads to a similar to 4-fold increase in the surface Na peak intensity. This value is significantly higher than what would be expected from high temperature annealing alone, which has been linked to improvements in surface morphology and device efficiency in CIGS solar cells. We use Energy Dispersive X-ray Spectroscopy (EDS) to measure the solid-state transport of Na within CIS films with and without passivation. EDS spectra on CIS film cross-sections reveals a saddle-shaped Na profile in the as fabricated films and a concentration gradient towards the film surface in the passivated films, with 20% higher surface Na content compared with the unpassivated films. We employ Hybrid (B3PW91) Density Functional Theory (DFT) to gain insight into energetics of Na defects, which demonstrate a driving force for Na diffusion from bulk towards the surface. DFT Calculations with TOP:S-like molecules on the same surfaces reveal a similar to 1eV lower formation energy for the Na-cu defect. The experiments and computations in this work suggest that TOP:S passivation promotes Na diffusion towards CIS film surfaces and stabilizes surface Na defects, which leads to the observed substantial decrease in surface recombination. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.