Characteristics of Atomic-Layer-Deposited HfO2 Films by Using a Remote Plasma on Pre-Deposited Hf Metal Layer

Hyungseok Hong,전형탁,Honggyu Kim,Hyungchul Kim,Sanghyun Woo,Seokhoon Kim,Seokhwan Bang,Seungjun Lee,Sunyeol Jeon,Wooho Jeong 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.4

We investigated the physical and the electrical properties of HfO₂ films grown by using a remote-plasma atomic layer deposition technique on a pre-deposited Hf metal layer. The Hf metal pre-deposited film retarded effectively the growth of an interfacial layer while the HfO₂ film without a Hf metal layer showed a growth of an interfacial layer. The as-deposited HfO₂ layers on thick Hf metal layers are crystallized while those on thin Hf metal layers remain amorphous. The pre-deposited Hf metal layer decreased the equivalent oxide thickness while it increased the crystallization temperature. The flat-band voltage (VFB) shifted in the negative direction with increasing pre-deposited Hf metal thickness and the effective fixed oxide charge density corresponding to the △VFB of the HfO₂ films increased with increasing pre-deposited Hf metal thickness. After annealing at 800℃, the VFB for the HfO₂ films shifted toward the ideal VFB and the effective fixed oxide charge decreased. The Hf pre-deposition technique was found to be effective in reducing the EOT by suppressing interfacial layer growth while the electrical properties, such as the leakage current density and the effective fixed oxide charge density, were degraded. We investigated the physical and the electrical properties of HfO₂ films grown by using a remote-plasma atomic layer deposition technique on a pre-deposited Hf metal layer. The Hf metal pre-deposited film retarded effectively the growth of an interfacial layer while the HfO₂ film without a Hf metal layer showed a growth of an interfacial layer. The as-deposited HfO₂ layers on thick Hf metal layers are crystallized while those on thin Hf metal layers remain amorphous. The pre-deposited Hf metal layer decreased the equivalent oxide thickness while it increased the crystallization temperature. The flat-band voltage (VFB) shifted in the negative direction with increasing pre-deposited Hf metal thickness and the effective fixed oxide charge density corresponding to the △VFB of the HfO₂ films increased with increasing pre-deposited Hf metal thickness. After annealing at 800℃, the VFB for the HfO₂ films shifted toward the ideal VFB and the effective fixed oxide charge decreased. The Hf pre-deposition technique was found to be effective in reducing the EOT by suppressing interfacial layer growth while the electrical properties, such as the leakage current density and the effective fixed oxide charge density, were degraded.

Hafnium metallocene compounds used as cathode interfacial layers for enhanced electron transfer in organic solar cells

Park, Keunhee,Oh, Seungsik,Jung, Donggeun,Chae, Heeyeop,Kim, Hyoungsub,Boo, Jin-Hyo Springer 2012 NANOSCALE RESEARCH LETTERS Vol.7 No.1

<P>We have used hafnium metallocene compounds as cathode interfacial layers for organic solar cells [OSCs]. A metallocene compound consists of a transition metal and two cyclopentadienyl ligands coordinated in a sandwich structure. For the fabrication of the OSCs, poly[3,4-ethylenedioxythiophene]:poly(styrene sulfonate), poly(3-hexylthiophene-2,5-diyl) + [6,6]-phenyl C<SUB>61 </SUB>butyric acid methyl ester, bis-(ethylcyclopentadienyl)hafnium(IV) dichloride, and aluminum were deposited as a hole transport layer, an active layer, a cathode interfacial layer, and a cathode, respectively. The hafnium metallocene compound cathode interfacial layer improved the performance of OSCs compared to that of OSCs without the interfacial layer. The current density-voltage characteristics of OSCs with an interfacial layer thickness of 0.7 nm and of those without an interfacial layer showed power conversion efficiency [PCE] values of 2.96% and 2.34%, respectively, under an illumination condition of 100 mW/cm<SUP>2 </SUP>(AM 1.5). It is thought that a cathode interfacial layer of an appropriate thickness enhances the electron transfer between the active layer and the cathode, and thus increases the PCE of the OSCs.</P>

Improved hydrogenated amorphous silicon thin-film solar cells realized by replacing <i>n</i>-type Si layer with PFN interfacial layer

Ryu, Seung Yoon,Seo, Ji hoon,Hafeez, Hassan,Song, Myungkwan,Shin, Jun Young,Kim, Dong Hyun,Jung, Yong Chan,Kim, Chang-Su Elsevier 2017 Synthetic metals Vol.228 No.-

<P><B>Abstract</B></P> <P>Improvement in the device performance of hydrogenated amorphous silicon (a-Si:H) thin-film solar cells (TFSCs) without hazardous doping gases and complex processes has been a long-standing aim for many researchers. In this work, we replaced the <I>n</I>-type Si layer in an a-Si:H TFSC with an interfacial dipole layer of conjugated polymer electrolyte material, poly [(9,9-bis(3′-(<I>N</I>,<I>N</I>-dimethylamino) propyl)-2,7-fluorene)-<I>alt</I>-2,7-(9,9-dioctylfluorene) (PFN), while keeping the conventional layer scheme. The addition of PFN eliminated the process complexity, improved the device performance, and generated a built-in potential (<I>V<SUB>bi</SUB> </I>) across the <I>p</I>-type Si layer. The power conversion efficiency of the optimized device reached a maximum of 7.17%, which is significant when using a toxicant-free layer. The open-circuit voltage was improved to 0.80V from 0.47V in comparison to a reference a-Si:H TFSC without PFN, and the stability in light and dark conditions were greatly enhanced. The fill factor was increased from 0.45 to 0.59 because of the enhancement in shunt/series resistance. The improvement in device performance is mainly due to the creation of an interfacial dipole by the PFN layer, which generated the <I>V<SUB>bi</SUB> </I> across the <I>p</I>-type Si layer, decreased the potential barrier between the i-Si layer and aluminum cathode, and consequently reduced the defects resulting from the coating of the i-Si layer and enhanced electron extraction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Improvement in device performance of hydrogenated amorphous silicon (a-Si:H) thin-film solar cells (TFSCs). </LI> <LI> Replacement of <I>n</I>-type Si layer with PFN as an interfacial layer in conventional a-Si:H TFSCs. </LI> <LI> Eliminating the use of hazardous <I>n</I>-type doping gases. </LI> <LI> Induced interfacial dipole for enhanced charge transfer and electron extraction. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

INFLUENCE OF INVESTMENT/CERAMIC INTERACTION LAYER ON INTERFACIAL TOUGHNESS OF BODY CERAMIC BONDED TO LITHIA-BASED CERAMIC

Park, Ju-Mi The Korean Academy of Prosthodonitics 2006 대한치과보철학회지 Vol.44 No.6

Statement of problem. Interfacial toughness is important in the mechanical property of layered dental ceramics such as core-veneered all-ceramic dental materials. The interfaces between adjacent layers must be strongly bonded to prevent delamination, however the weak interface makes delamination by the growth of lateral cracks along the interface. Purpose. The purpose of this study was to determine the effect of the reaction layer on the interfacial fracture toughness of the core/veneer structure according to the five different divesting. Materials and methods. Thirty five heat-pressed Lithia-based ceramic core bars (IPS Empress 2), $20mm{\times}3mm{\times}2mm$ were made following the five different surface divesting conditions. G1 was no dissolution or sandblasting of the interaction layer. G2 and G3 were dissolved layer with 0.2% HF in an ultrasonic unit for 15min and 30 min. G4 and G5 were dissolved layer for 15min and 30min and then same sandblasting for 60s each. We veneered bilayered ceramic bars, $20mm{\times}2.8mm{\times}3.8mm$(2mm core and 1.8mm veneer), according to the manufacturer's instruction. After polishing the specimens through $1{\mu}m$ alumina, we induced five cracks for each of five groups within the veneer close to interface under an applied indenter load of 19.6N with a Vickers microhardness indenter. Results. The results from Vickers hardness were the percentage of delamination G1:55%, G2:50%, G3:35%, G4:0% and G5:0%. SEM examination showed that the mean thickness of the reaction layer were G1 $93.5{\pm}20.6{\mu}m$, G2 $69.9{\pm}14.3{\mu}m$, G3 $59.2{\pm}20.2{\mu}m$, G4 $0.61{\pm}1.44{\mu}m$ G5 $0{\pm}0{\mu}m$. The mean interfacial delamination crack lengths were G1 $131{\pm}54.5{\mu}m$, G2 $85.2{\pm}51.3{\mu}m$, and G3 $94.9{\pm}81.8{\mu}m$. One-way ANOVA showed that there was no statistically significant difference in interfacial crack length among G1, G2 and G3(p> 0.05). Conclusion. The investment reaction layer played important role at the interfacial toughness of body ceramic bonded to Lithia-based ceramic.

Layering시 복합레진 층간의 계면 결합에서 oxygen inhibition layer가 필수적인가?

김선영,조병훈,백승호,이인복 大韓齒科保存學會 2008 Restorative Dentistry & Endodontics Vol.33 No.4

본 연구의 목적은 여러 가지 계면조건의 변화를 통해서 layering 시 복합레진 층간의 결합에 oxygen inhibition layer (OIL)가 필수적인지를 고찰해보는 것이다. 가로 × 세로 × 두께가 16 × 28 × 2.5 ㎜인 알루미늄판에 지름 3.7 ㎜의 구멍을 형성하여 몰드를 제작하고 다음과 같이 복합레진 (Z-250, 3M ESPE)을 충전하여 광중합하였다. 1 군: 하층판에 복합레진을 충전하고 광중합 한 후, 상층판을 접합하고 레진을 충전하여 광중합을 하였다 (OIL를 남김). 2군: 하층판에 복합레진을 충전하고 팡중합 한 후 acetone에 적신 cotton으로 문질러서 OIL를 제거하고 상층판을 접합하여 복합레진을 충전하고 광중합을 하였다 (OIL를 제거). 3군: 하층판에 복합레진을 충전하고 Mylar strip을 접합하여 공기와의 접촉을 차단한 후 광중합을 하였다. Mylar strip을 제거하고 상층판을 접합 후 복합레진을 충전하여 광중합을 하였다 (OIL형성을 억제). 4군: 하층판에 복합레진을 충전하고 광중합 한 후 glycerin을 OIL표면에 도포하고 다시 광중합하였다. 상층판을 접합하여 복합레진을 충전하고 광중합을 하였다 (OIL를 중합). 5군 (대조군): 하층판과 상층판의 경계에 복합레진층의 계면이 위치하지 않도록 복합레진을 bulk충전하였다 (계면 형성 없이 bulk 충전한 복합레진). 24시간 100% 습도에서 보관 후 상층판과 하층판 사이의 계면 전단결합강도를 측정하고 파절 양상을 관찰하였다. 계면을 통한 중합과정의 확산을 관찰하기 위하여 제조한 광개시제가 들어있지 않은 실험적 복합레진 (Exp_Com)을 몰드에 충전하고 상부에 flowable 복합 레진 (Aelite Flow) 또는 접착레진 (ScotchBond Multipurpose)을 접촉시킨 후 광조사하였다. 몰드내의 미중합된 Exp_Com을 acetone bath 에서 5 분 동안 제거한 후 몰드내에 다시 Aelite Flow를 충전하고 광중합을 시행하였다. 경화된 복합레진 시편의 단면을 관찰하여 ExP_Com 층의 두께를 측정하였다. OIL를 배제하거나 중합시킨 2-4 군은 OIL이 존재하는 1 군과 통계적으로 유의한 결합강도의 차이를 보이지 않았으며, Mylar strip을 이용하여 OIL의 생성을 억제했던 3 군과 glycerin을 도포하여 OIL를 중합시킨 4 군은 계면을 생성하지 않은 대조군인 5 군과도 통계적으로 유의한 차이를 보이지 않았다. 중합과정의 확산에 의해 중합개시제가 포함되지 않은 Exp_Com내에 중합된 층이 생겨난 것을 시각적으로 확인할 수 있었으며, Exp_Com의 중합층 두께는 flowable 레진의 경우 20,95 (0.90) um였고 접착레진의 경우 42.13 (2.09) 였다. This study was aimed to investigate whether an oxygen inhibition layer (OIL) is essential for the interfacial bonding between resin composite layers or not. A composite (Z-250, 3M ESPE) was filled in two layers using two aluminum plate molds with a hole of 3.7 ㎜ diameter. The surface of first layer of cured composite was prepared by one of five methods as followings. thereafter second layer of composite was filled and cured: Group 1 - OIL is allowed to remain on the surface of cured composite; Group 2 - OIL was removed by rubbing with acetone-soaked cotton; Group 3 - formation of the OIL was inhibited using a Mylar strip; Group 4 - OIL was covered with glycerin and light-cured; Group 5 (control) - composite was bulk-filled in a layer. The interfacial shear bond strength between two layers was tested and the fracture modes were observed. To investigate the propagation of polymerization reaction from active area having a photo-initiator to inactive area without the initiator, a flowable composite (Aelite Flow) or an adhesive resin (Adhesive of ScotchBond Multipurpose) was placed over an experimental composite (Exp_Com) which does not include a photoinitiator and light-cured. After sectioning the specimen, the cured thickness of the Exp_Com was measured. The bond strength of group 2, 3 and 4 did not show statistically significant difference with group 1. Groups 3 and 4 were not statistically significant different with control group 5. The cured thicknesses of Exp_Com under the flowable resin and adhesive resin were 20.95 (0.90) um and 42.13 (2.09), respectively.

이중 나노 계면층을 적용한 고효율 고분자 태양 전지 소자 연구

이영인,박병주,Lee, Young-In,Park, Byoung-Choo 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.1

We introduced nanoscale interfacial layers between the PV layer and the cathode in poly (3-hexylthiophene):methanofullerene bulk-heterojunction polymer photovoltaic (PV) cells. The nanoscale double interfacial layers were made of ultrathin poly (oxyethylenetridecylether) surfactant and low-work-function alloy-metal of Al:Li layers. It was found that the nanoscale interfacial layers increase the photovoltaic performance, i.e., increasing short-circuit current density and fill factor with improved device stability. For PV cells with the nanoscale double interfacial layers, an increase in power conversion efficiency of $4.18{\pm}0.24%$ was achieved, compared to that of the control devices ($3.89{\pm}0.08%$) without the double interfacial layers.

Interfacial Engineering Importance of Bilayered ZnO Cathode Buffer on the Photovoltaic Performance of Inverted Organic Solar Cells.

Ambade, Rohan B,Ambade, Swapnil B,Mane, Rajaram S,Lee, Soo-Hyoung American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.15

<P>The role of cathode buffer layer (CBL) is crucial in determining the power conversion efficiency (PCE) of inverted organic solar cells (IOSCs). The hallmarks of a promising CBL include high transparency, ideal energy levels, and tendency to offer good interfacial contact with the organic bulk-heterojunction (BHJ) layers. Zinc oxide (ZnO), with its ability to form numerous morphologies in juxtaposition to its excellent electron affinity, solution processability, and good transparency is an ideal CBL material for IOSCs. Technically, when CBL is sandwiched between the BHJ active layer and the indium-tin-oxide (ITO) cathode, it performs two functions, namely, electron collection from the photoactive layer that is effectively carried out by morphologies like nanoparticles or nanoridges obtained by ZnO sol-gel (ZnO SG) method through an accumulation of individual nanoparticles and, second, transport of collected electrons toward the cathode, which is more effectively manifested by one-dimensional (1D) nanostructures like ZnO nanorods (ZnO NRs). This work presents the use of bilayered ZnO CBL in IOSCs of poly(3-hexylthiophene) (P3HT)/[6, 6]-phenyl-C60-butyric acid methyl ester (PCBM) to overcome the limitations offered by a conventionally used single layer CBL. We found that the PCE of IOSCs with an appropriate bilayer CBL comprising of ZnO NRs/ZnO SG is 18.21% higher than those containing ZnO SG/ZnO NRs. We believe that, in bilayer ZnO NRs/ZnO SG, ZnO SG collects electrons effectively from photoactive layer while ZnO NRs transport them further to ITO resulting significant increase in the photocurrent to achieve highest PCE of 3.70%. The enhancement in performance was obtained through improved interfacial engineering, enhanced electrical properties, and reduced surface/bulk defects in bilayer ZnO NRs/ZnO SG. This study demonstrates that the novel bilayer ZnO CBL approach of electron collection/transport would overcome crucial interfacial recombination issues and contribute in enhancing PCE of IOSCs.</P>

Interfacial layer material derived from dialkylviologen and sol-gel chemistry for polymer solar cells

Jo, M.Y.,Ha, Y.E.,Kim, J.H. Elsevier Science 2013 ORGANIC ELECTRONICS Vol.14 No.3

Sol-gel processible organosilicate material based on dialkylviologen (1,1-(bis-trimethoxysilane)-[4,4']bipyridium dibromide (bis-trimethoxypropylsilane)-yl-viologen, PV-Si) was synthesized and used as an interfacial layer material for polymer solar cells based on poly(3-hexylthiophene): [6,6]-phenyl-C<SUB>61</SUB>-butyric acid methyl ester (P3HT:PCBM). PV-Si is very good soluble in polar protic solvents because of two pyrinium bromide salts and PV-Si pre-polymer can be easily prepared by sol-gel chemistry under the mild acidic conditions. From the ultraviolet spectroscopy (UPS) study, the reduction of the work function of Al and ITO is observed by the formation of interface dipole, which is induced by the thin film of thermally cured PV-Si pre-polymer (cPV-Si) at 180<SUP>o</SUP>C. The open circuit voltage (V<SUB>oc</SUB>) of conventional type polymer solar cell (CPSC) with a structure of ITO/active layer (P3HT:PCBM)/cPV-Si(<5nm)/Al is 0.58V, which is higher than the CPSC without cPV-Si (0.55V). This indicates that the favorable interface dipole is generated by the thin film of cPV-Si. Besides, the power conversion efficiency (PCE) of CPSC with cPV-Si reaches at 2.90%, which is higher than that of the device without cPV-Si (2.69%). Surprisingly, the PCE and the short circuit current (J<SUB>sc</SUB>) of inverted type polymer solar cell (IPSC) with a structure of ITO/cPV-Si (<5nm)/active layer/WO<SUB>3</SUB>/Ag are 2.83% and -9.19mA/cm<SUP>2</SUP>, respectively, which are higher than those of the device with ZnO (2.51% and -8.63mA/cm<SUP>2</SUP>) as an electron transporting/injecting layer. This is due to that the work function of ITO is also reduced by the formation of interface dipole. The IPSC with cPV-Si as an interfacial layer (IFL) shows very good rectification and a contact property as well. From the results, the thin layer of cPV-Si is potential material for an IFL for either CPSC or IPSC. Especially, ZnO can be replaced by cPV-Si because of their improved device performances and pretty low processing temperature.

Highly Tunable Interfacial Adhesion of Glass Fiber by Hybrid Multilayers of Graphene Oxide and Aramid Nanofiber

Park, Byeongho,Lee, Wonoh,Lee, Eunhee,Min, Sa Hoon,Kim, Byeong-Su American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.5

<P>The performance of fiber-reinforced composites is governed not only by the nature of each individual component comprising the composite but also by the interfacial properties between the fiber and the matrix. We present a novel layer-by-layer (LbL) assembly for the surface modification of a glass fiber to enhance the interfacial properties between the glass fiber and the epoxy matrix. Solution-processable graphene oxide (GO) and an aramid nanofiber (ANF) were employed as active components for the LbL assembly onto the glass fiber, owing to their abundant functional groups and mechanical properties. We found that the interfacial properties of the glass fibers uniformly coated with GO and ANF multilayers, such as surface free energy and interfacial shear strength, were improved by 23.6% and 39.2%, respectively, compared with those of the bare glass fiber. In addition, the interfacial adhesion interactions between the glass fiber and the epoxy matrix were highly tunable simply by changing the composition and the architecture of layers, taking advantage of the versatility of the LbL assembly.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-5/am5082364/production/images/medium/am-2014-082364_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5082364'>ACS Electronic Supporting Info</A></P>

Small-Molecules Electrolytes as an Interfacial layer in Polymer Solar Cells

김동근,김윤환,( Nadhila Sylvianti ),( Mutia Anissa Marsya ),안병현,김주현 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

To enhance the efficiency of polymer solar cells (PSCs), applying for electrolytes as an interfacial layer has been extensively studied in recently. In our study, it has been reported that using synthetic compounds called C-4 and C-6 as an interfacial layer can improve the power conversion efficiency (PCE) of PSCs. These interfacial layers can reduce work function of the cathode, contact resistance and improve the performance of PSCs. Herein, we investigate the photovoltaic properties of PSCs with C-4 and C-6 as an interfacial layer.