Transparent bifacial a-Si:H solar cells employing silver oxide embedded transparent rear electrodes for improved transparency

Jo, Hyunjin,Yang, Jo-Hwa,Lee, Ji-hoon,Lim, Jung-Wook,Lee, Jaesung,Shin, Myunhun,Ahn, Ji-Hoon,Kwon, Jung-Dae Elsevier 2018 SOLAR ENERGY -PHOENIX ARIZONA THEN NEW YORK- Vol.170 No.-

<P><B>Abstract</B></P> <P>We developed a transparent oxide–metal–oxide (OMO) structure using aluminum-doped zinc oxide and oxidized silver (AgO<SUB>x</SUB>) as a transparent electrode of a hydrogenated amorphous silicon (a-Si:H) thin-film solar cell for use in building-integrated photovoltaic (BIPV) windows. The oxygen (O<SUB>2</SUB>) addition (O<SUB>2</SUB> flow rate) was optimized for a metal-to-dielectric intermediate-phase AgO<SUB>x</SUB> OMO to have high transparency and high conductivity, which were confirmed by finite-difference time-domain simulation. Using the AgO<SUB>x</SUB> OMO as a rear electrode, transparent a-Si:H solar cells were fabricated for BIPV window application. The performance of the fabricated cells showed highest bifacial efficiency (b-<I>η</I>) of 7.87% at AgO<SUB>x</SUB> OMO of 1 sccm, and highest average transmittance (<I>T</I> <SUB>500–800</SUB>, i.e., wavelength range: 500–800 nm) of 21.9% at AgO<SUB>x</SUB> OMO of 3 sccm, i.e., improvements from b-<I>η</I> = 7.42% and <I>T</I> <SUB>500–800</SUB> = 18.8% at Ag OMO of 0 sccm. The cell with the optimized AgO<SUB>x</SUB> OMO (3 sccm) achieved b-<I>η</I> = 7.69% and the best figure of merit (product of b-<I>η</I> and <I>T</I> <SUB>500–800</SUB>) of 169%, i.e., 30% higher than the Ag OMO cell (139%). The developed AgO<SUB>x</SUB> OMO electrodes could be used in BIPV windows or in other optical devices requiring both high transparency and high conductivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> AgO<SUB>x</SUB> is introduced in a transparent oxide-metal-oxide (OMO) structure. </LI> <LI> Oxidization of AgO<SUB>x</SUB> is optimized for high transparency and efficiency of transparent a-Si:H solar cells. </LI> <LI> Optical property of AgO<SUB>x</SUB>-OMO is investigated experimentally and theoretically. </LI> <LI> Bifacial operation property of a-Si:H solar cells was presented. </LI> </UL> </P>

Highly transparent and conductive oxide-metal-oxide electrodes optimized at the percolation thickness of AgO_x for transparent silicon thin-film solar cells

Jo, Hyunjin,Yang, Jo-Hwa,Choi, Soo-Won,Park, Jaeho,Song, Eun Jin,Shin, Myunhun,Ahn, Ji-Hoon,Kwon, Jung-Dae Elsevier 2019 Solar energy materials and solar cells Vol.202 No.-

<P><B>Abstract</B></P> <P>Highly transparent and conductive oxide-metal-oxide (OMO) electrodes comprising aluminum-doped zinc-oxide (AZO) and ultrathin Ag or oxygen (O<SUB>2</SUB>)-doped Ag (AgO<SUB>x</SUB>) metal layers were fabricated for use in thin-film silicon solar cells. The surface morphologies of the metal layers and the transparencies and conductivities of OMO electrodes were investigated near the percolation thickness values of the metal layers. The percolation metal thickness, which means the metal layer is morphologically continuous, could be used to optimize the transparent OMO electrode. Additionally, thin Ag-based OMO (AgO<SUB>x</SUB> OMO) with superior performance could be fabricated by adding O<SUB>2</SUB>. The optimized AgO<SUB>x</SUB> OMO electrodes yielded the highest average transmittance (<I>T</I> <SUB>avg</SUB>) of 93.5% and the lowest average optical loss (OL<SUB>avg</SUB>) of 1.01% within 500–800 nm at the percolation thickness of ~6 nm, thus, maintaining low conductivity. These outcomes were superior to the responses of the percolated Ag OMO (<I>T</I> <SUB>avg</SUB> = 87.2%; OL<SUB>avg</SUB> = 1.01%). Using the OMO structure at the rear electrode, transparent hydrogenated amorphous silicon thin-film solar was fabricated for building integrated photovoltaic windows. The best figure-of-merit (FOM; equal to the product of <I>T</I> <SUB>avg</SUB> and efficiency <I>η</I>) values of the OMO-based transparent solar cells could be obtained for percolated OMO structures. The cells using AgO<SUB>x</SUB> OMO (AgO<SUB>x</SUB> cells) performed better than the Ag cells; the best FOMs of AgO<SUB>x</SUB> and Ag cells were 140.8 (<I>T</I> <SUB>avg</SUB> = 27.8%; <I>η</I> = 5.51%) and 104.6% (<I>T</I> <SUB>avg</SUB> = 18.9%; <I>η</I> = 5.54%), respectively. These results could contribute to the development of high-performance transparent solar cells or optoelectronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Transparent/conductive oxide-metal-oxide (OMO) electrodes were fabricated. </LI> <LI> Oxygen doping effects in thin Ag film is investigated. </LI> <LI> Optimization of OMO electrodes was based on the percolation metal thickness. </LI> <LI> Thin oxygen-doped Ag-based OMO electrodes yielded better performances. </LI> <LI> Optimized electrodes can be used in high-performance transparent solar cells/devices. </LI> </UL> </P>

산소플라즈마 전처리된 Polyethylene Naphthalate 기판 위에 증착된 ZnO:Ga 투명전도막의 특성

김병국,김정연,오병진,임동건,박재환,우덕현,권순용,Kim, Byeong-Guk,Kim, Jeong-Yeon,Oh, Byoung-Jin,Lim, Dong-Gun,Park, Jae-Hwan,Woo, Duck-Hyun,Kweon, Soon-Yong 한국재료학회 2010 한국재료학회지 Vol.20 No.4

Transparent conducting oxide (TCO) films are widely used for optoelectronic applications. Among TCO materials, zinc oxide (ZnO) has been studied extensively for its high optical transmission and electrical conduction. In this study, the effects of $O_2$ plasma pretreatment on the properties of Ga-doped ZnO films (GZO) on polyethylene naphthalate (PEN) substrate were studied. The $O_2$ plasma pretreatment process was used instead of conventional oxide buffer layers. The $O_2$ plasma treatment process has several merits compared with the oxide buffer layer treatment, especially on a mass production scale. In this process, an additional sputtering system for oxide composition is not needed and the plasma treatment process is easily adopted as an in-line process. GZO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion between the PEN substrate and the GZO film, the $O_2$ plasma pre-treatment process was used prior to GZO sputtering. As the RF power and the treatment time increased, the contact angle decreased and the RMS surface roughness increased significantly. It is believed that the surface energy and adhesive force of the polymer surfaces increased with the $O_2$ plasma treatment and that the crystallinity and grain size of the GZO films increased. When the RF power was 100W and the treatment time was 120 sec in the $O_2$ plasma pretreatment process, the resistivity of the GZO films on the PEN substrate was $1.05\;{\times}\;10^{-3}{\Omega}-cm$, which is an appropriate range for most optoelectronic applications.

Review on the Synthesis and Antioxidation of Cu Nanowires for Transparent Conductive Electrodes

Jia Feng Chao,Yong Qiang Meng,Jingbing Liu,Qian Qian Zhang,Hao Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.4

Transparent conducting films based on solution-synthesized copper nanowires (Cu NWs) are considered to be an attractive alternative to indium tin oxide (ITO) due to the relative abundance of Cu and the low cost of solution-phase NW coating processes. Moreover, transparent electrodes tend to be flexible. This makes Cu NWs more attractive because ITO is brittle and can not meet the requirements of flexibility. For Cu NWs, aspect ratio is an important property. Cu NWs can be directly prepared by chemical reduction with various reducing agents and suitable capping agents. In general, the selectivity of the capping agent is very important for the formation of one-dimensional nanostructures because it plays a major role in the thermodynamic regulations and growth kinetics that influence the geometry and morphology of the crystal facets. Therefore, different aspect ratios are formed. Conductivity is the most important property for transparent electrodes. Organic pickling, annealing and glare pulses have a certain improvement in conductivity. Meanwhile, it is also essential to increase the oxidation resistance of the transparent electrode. The reduction of graphene oxide (r-GO), the coating of metal and polymer improve the oxidation resistance of the transparent electrode to varying degrees. This paper reviews the effect of different capping agents on the aspect ratio of NWs, and the effects of different post-treatments on oxidation resistance and conductivity of transparent electrodes.

Improved Transparent-Conducting Properties in N₂- and H₂-annealed GaZnO Thin Films Grown on Glass Substrates

이영민,김득영,이세준 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.1

The effects of N2- and H2-annealing on the transparent-conducting properties of Ga-doped ZnO (GaZnO) were examined. The as-grown GaZnO thin film, which was deposited on a soda-lime glass substrate by r.f. magnetron sputtering, exhibited moderate transparent-conducting properties: a resistivity of 100 -cm and an optical transmittance of 86%. After annealing in N2 or H2,the GaZnO samples showed great improvements in both the electrical and the optical properties. Particularly, in the H2-annealed sample, a dramatic decrease in the resistivity (7 × 10.4 -cm)with a considerable increase in the carrier concentration (4.22 × 1021 cm.3) was observed. This is attributed to both an increase in the number of Ga-O bonds and a reduction in the number of chemisorbed oxygen atoms though H2 annealing. The sample revealed an enhanced optical transmittance (91%), which comes from the Burstein-Moss effect. Namely, a blue-shift of the optical absorption edge, which results from the increased carrier concentration, was observed in the H2-annealed sample. The results suggest that hydrogen annealing can help improve the transparentconducting properties of GaZnO via a modification of the electrochemical bonding structures. The effects of N2- and H2-annealing on the transparent-conducting properties of Ga-doped ZnO (GaZnO) were examined. The as-grown GaZnO thin film, which was deposited on a soda-lime glass substrate by r.f. magnetron sputtering, exhibited moderate transparent-conducting properties: a resistivity of 100 -cm and an optical transmittance of 86%. After annealing in N2 or H2,the GaZnO samples showed great improvements in both the electrical and the optical properties. Particularly, in the H2-annealed sample, a dramatic decrease in the resistivity (7 × 10.4 -cm)with a considerable increase in the carrier concentration (4.22 × 1021 cm.3) was observed. This is attributed to both an increase in the number of Ga-O bonds and a reduction in the number of chemisorbed oxygen atoms though H2 annealing. The sample revealed an enhanced optical transmittance (91%), which comes from the Burstein-Moss effect. Namely, a blue-shift of the optical absorption edge, which results from the increased carrier concentration, was observed in the H2-annealed sample. The results suggest that hydrogen annealing can help improve the transparentconducting properties of GaZnO via a modification of the electrochemical bonding structures.

RF 마그네트론 스퍼터링을 이용한 p 타입 투명전도 산화물 SrCu₂O₂ 박막의 제조

석혜원,김세기,이현석,임태영,황종희,최덕균,Seok, Hye-Won,Kim, Sei-Ki,Lee, Hyun-Seok,Lim, Tae-Young,Hwang, Jong-Hee,Choi, Duck-Kyun 한국재료학회 2010 한국재료학회지 Vol.20 No.12

Most TCOs such as ITO, AZO(Al-doped ZnO), FTO(F-doped $SnO_2$) etc., which have been widely used in LCD, touch panel, solar cell, and organic LEDs etc. as transparent electrode material reveal n-type conductivity. But in order to realize transparent circuit, transparent p-n junction, and introduction of transparent p-type materials are prerequisite. Additional prerequisite condition is optical transparency in visible spectral region. Oxide based materials usually have a wide optical bandgap more than ~3.0 eV. In this study, single-phase transparent semiconductor of $SrCu_2O_2$, which shows p-type conductivity, have been synthesized by 2-step solid state reaction at $950^{\circ}C$ under $N_2$ atmosphere, and single-phase $SrCu_2O_2$ thin films of p-type TCOs have been deposited by RF magnetron sputtering on alkali-free glass substrate from single-phase target at $500^{\circ}C$, 1% $H_2$/(Ar + $H_2$) atmosphere. 3% $H_2$/(Ar + $H_2$) resulted in formation of second phases. Hall measurements confirmed the p-type nature of the fabricated $SrCu_2O_2$ thin films. The electrical conductivity, mobility of carrier and carrier density $5.27{\times}10^{-2}S/cm$, $2.2cm^2$/Vs, $1.53{\times}10^{17}/cm^3$ a room temperature, respectively. Transmittance and optical band-gap of the $SrCu_2O_2$ thin films revealed 62% at 550 nm and 3.28 eV. The electrical and optical properties of the obtained $SrCu_2O_2$ thin films deposited by RF magnetron sputtering were compared with those deposited by PLD and e-beam.

Optical and Electrical Properties of Oxide Multilayers

Han, Sangmin,Yu, Jiao Long,Lee, Sang Yeol The Korean Institute of Electrical and Electronic 2016 Transactions on Electrical and Electronic Material Vol.17 No.4

Oxide/metal/oxide (OMO) thin films were fabricated using amorphous indium-gallium-zinc-oxide (a-IGZO) and an Ag metal layer on a glass substrate at room temperature. The optical and electrical properties of the a-IGZO/Ag/a-IGZO samples changed systemically depending on the thickness of the Ag layer. The transmittance in the visible range tends to decrease as the Ag thickness increases while the resistivity, carrier concentration, and Hall mobility tend to improve. The a-IGZO/Ag (13 nm)/a-IGZO thin film with the optimum Ag thickness showed an average transmittance (T_av) of 71.7%, resistivity of 6.63 × 10⁻⁵ Ω·cm and Hall mobility of 15.22 cm²V⁻¹s⁻¹.

산화아연의 전이금속 도핑 및 밴드구조 변화에 대한 제일원리계산연구

강영호(Youngho Kang) 한국세라믹학회 2023 세라미스트 Vol.26 No.3

Transparent conducting oxides (TCOs) have both the electrical conductivity of a metal and the optical transparency of an insulator. Due to this unique feature, TCO is utilized in various applications such as flat panel displays, solar cells, light emitting diodes, and smart windows. At present, Sn-doped In₂O₃ (ITO) is the most widely used in the TCO market because of the superior materials properties. However, due to the demand for higher conductivity, instability of indium supply and high price, research to find new TCO materials has been continuously conducted. In this study, to develop a new TCO based on ZnO, we investigate the thermal stability of the transition metal dopants Sc and V and their effect on the band structure of ZnO using first-principles calculations. Our results show that Sc and V are efficient donors that can generate one free electron by substituting Zn when doped into ZnO. Furthermore, by analyzing the band structure of the doped system and calculating the electron effective mass, we show that Sc and V doping can be an important strategy to develop ZnO-based high-performance TCOs.

Heating Characteristics of Transparent Films Prepared with Conductive Composite Materials

최윤형,오원태 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.1

Transparent heating film was fabricated with the conductive coating solution including silver nanowire and graphene oxide. Visible transmittance, electric resistance, and heating temperature were analyzed on the as-prepared film. Transparent heating fi lm was fabricated with a resistance value of 100 Ω or less, and the visible transmittance was adjusted at a level of 90% or less according to the loading of Ag nanowire. The heating temperature was stably increased throughout the film up to 100 °C or more in proportion to the applied DC voltage.

Transparent Conductive Gallium-doped Indium Oxide Nanowires for Optoelectronic Applications

S. H. Mohamed 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.6

Undoped and Ga-doped In2O3 nanowires (NWs) were synthesized by using vapor-liquid-solid (VLS) growth and were characterized as transparent conductive oxides for future generations of optoelectronic devices. A low amount of Ga was obtained due to the low solubility of Ga₂O₃ in In₂O₃. The incorporation of Ga into In₂O₃ nanowires decreases the grain size, the transmittance and the optical band gap. The Ga-doped In₂O₃ NWs exhibited a low sheet resistance of 12.2 ± 2 Ω/□ and a mean transmittance value in the visible region of 77.1, which favor its use as a promising transparent conductive oxide.