The effect of different TiO2 passivating layers on the photovoltaic performance of dye-sensitized solar cells

진영삼,최형욱 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.2

The aim of this study is to prevent back transfer of electrons due to direct contact between the electrolyte and the FTO glass substrate using a TiO2 passivating layer. The TiO2 sol was prepared by a sol-gel method, and the TiO2 was coated on the FTO glass by spin coating method. The crystalline structure was adjusted by various catalyst concentrations: 0.1 mol, 0.5 mol. As With an increase in the catalyst concentration, the crystalline structure of the TiO2 passivating layer become the rutile phase. A nanoporous TiO2 upper layer was deposited by a screen printing method on the TiO2 passivating layer. The optical transmittance and particle size of the TiO2 passivating layer depend on the crystalline structure of the TiO2 passivating layer. The dye-sensitized solar cell was influenced by the crystalline structure of the TiO2 passivating layer. The dye-sensitized solar cell using a TiO2 passivating layer of the rutile phase was measured to have a maximum conversion efficiency of 3.98% due to the effective prevention of an electron recombination to the electrolyte. The aim of this study is to prevent back transfer of electrons due to direct contact between the electrolyte and the FTO glass substrate using a TiO2 passivating layer. The TiO2 sol was prepared by a sol-gel method, and the TiO2 was coated on the FTO glass by spin coating method. The crystalline structure was adjusted by various catalyst concentrations: 0.1 mol, 0.5 mol. As With an increase in the catalyst concentration, the crystalline structure of the TiO2 passivating layer become the rutile phase. A nanoporous TiO2 upper layer was deposited by a screen printing method on the TiO2 passivating layer. The optical transmittance and particle size of the TiO2 passivating layer depend on the crystalline structure of the TiO2 passivating layer. The dye-sensitized solar cell was influenced by the crystalline structure of the TiO2 passivating layer. The dye-sensitized solar cell using a TiO2 passivating layer of the rutile phase was measured to have a maximum conversion efficiency of 3.98% due to the effective prevention of an electron recombination to the electrolyte.

Characteristics of surface passivation of ozone- and water-based Al₂O₃ films grown by atomic layer deposition for silicon solar cells

Cho, Young Joon,Chung, Kwun-Bum,Chang, Hyo Sik Elsevier 2018 THIN SOLID FILMS - Vol.649 No.-

<P><B>Abstract</B></P> <P>We investigated the effects of the thermal stability of atomic layer deposition (ALD) oxidants on the surface passivation of ALD-Al<SUB>2</SUB>O<SUB>3</SUB> film. The results showed good passivation at temperatures not greater than 780 °C. However, we found that Al<SUB>2</SUB>O<SUB>3</SUB> films with an ozone oxidant showed better surface passivation at high temperatures than the water-based samples. The Al<SUB>2</SUB>O<SUB>3</SUB> films with a water oxidant yielded an additional interfacial oxide upon high-temperature annealing. In the case of the ozone-based samples, the interfacial SiO bonds that formed during deposition were more stable. This structural change degraded chemical passivation, which increased the interface-trap density to ~10<SUP>12</SUP> eV<SUP>−1</SUP> cm<SUP>−2</SUP>. The passivation performance of ALD-Al<SUB>2</SUB>O<SUB>3</SUB> films showed that at temperatures over 780 °C the passivation quality was affected more by defective passivation at the Si/SiOx interface than by a negative-fixed charge.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We compared surface passivation of ozone- and water-based ALD-Al<SUB>2</SUB>O<SUB>3</SUB> film. </LI> <LI> Ozone-based ALD-Al<SUB>2</SUB>O<SUB>3</SUB> film shows excellent thermal stability for passivation. </LI> <LI> The passivation quality of O<SUB>3</SUB>-based Al<SUB>2</SUB>O<SUB>3</SUB> is affected by interface defect over 780 °C. </LI> <LI> Degradation of passivation performance was different according to ALD oxidants. </LI> </UL> </P>

Improvement of Long-Term Durability and Bias Stress Stability in p-Type SnO Thin-Film Transistors Using a SU-8 Passivation Layer

Young-Joon Han,Yong-Jin Choi,In-Tak Cho,Sung Hun Jin,Jong-Ho Lee,Hyuck-In Kwon IEEE 2014 IEEE electron device letters Vol.35 No.12

<P>We investigate the effects of ambient atmosphere on the electrical performance of p-type tin monoxide (SnO) thin-film transistors (TFTs), and present the effective method for the passivation of SnO TFTs using a SU-8 organic layer. The experimental data shows that the SnO TFTs without a passivation layer suffer from the electrical performance degradation under humid environments, which implies that the formation of the passivation layer is necessary in p-type SnO TFTs for the stable operation of the devices. The SU-8 organic layer was successfully incorporated as a passivation layer of SnO TFTs. The SnO TFTs with a SU-8 passivation layer exhibit very similar transfer characteristics with those without a passivation layer, and show much improved long-term durability and bias stress stability compared with the SnO TFTs without a passivation layer under air environments.</P>

Intrinsic Amorphous Silicon (a-Si:H) Thin Film Prepared by Using Remote Plasma Chemical Vapor Deposition Method and Used as a Passivation Layer for a Heterojunction Solar Cell

Minsung Jeon,Shuhei Yoshiba,Koichi Kamisako 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1

The hydrogenated amorphous silicon (a-Si:H) films used as intrinsic passivation layers were pre- pared using the radio-frequency remote-plasma chemical vapor deposition method under various deposition conditions for application to heterojunction solar cells. Their characteristics, such as their structural properties and carrier lifetimes, were investigated. When the substrate tempera- ture was set to 250℃, the optimal deposition gas ratio (rH = SiH4/H2) and the RF power were 1/15 and 80 W, respectively. Furthermore, to improve the passivation effect, we performed an annealing treatment. The highest improvement was displayed at an annealing temperature of 250℃. In the FT-IR analysis, the Si-H2 stretching mode, which means defects in the films, was shifted to Si-H stretching mode, which means a good quality film, after annealing treatment. Moreover, the highest carrier lifetime was 1.5 ms, which is higher value than the bulk lifetime of 900 us. From these results, we conclude that a combination of optimal deposition conditions and annealing treatment is essential to improve the surface and bulk passivation. The hydrogenated amorphous silicon (a-Si:H) films used as intrinsic passivation layers were pre- pared using the radio-frequency remote-plasma chemical vapor deposition method under various deposition conditions for application to heterojunction solar cells. Their characteristics, such as their structural properties and carrier lifetimes, were investigated. When the substrate tempera- ture was set to 250℃, the optimal deposition gas ratio (rH = SiH4/H2) and the RF power were 1/15 and 80 W, respectively. Furthermore, to improve the passivation effect, we performed an annealing treatment. The highest improvement was displayed at an annealing temperature of 250℃. In the FT-IR analysis, the Si-H2 stretching mode, which means defects in the films, was shifted to Si-H stretching mode, which means a good quality film, after annealing treatment. Moreover, the highest carrier lifetime was 1.5 ms, which is higher value than the bulk lifetime of 900 us. From these results, we conclude that a combination of optimal deposition conditions and annealing treatment is essential to improve the surface and bulk passivation.

Al₂O₃ Passivation Effect in HfO₂·Al₂O₃ Laminate Structures Grown on InP Substrates

Kang, Hang-Kyu,Kang, Yu-Seon,Kim, Dae-Kyoung,Baik, Min,Song, Jin-Dong,An, Youngseo,Kim, Hyoungsub,Cho, Mann-Ho American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.20

<P>The passivation effect of an Al2O3 layer on the electrical properties was investigated in HfO2-Al2O3 laminate structures grown on indium phosphide (InP) substrate by atomic-layer deposition. The chemical state obtained using high-resolution X-ray photoelectron spectroscopy showed that interfacial reactions were dependent on the presence of the Al2O3 passivation layer and its sequence in the HfO2-Al2O3 laminate structures. Because of the interfacial reaction, the Al2O3/HfO2/Al2O3 structure showed the best electrical characteristics. The top Al2O3 layer suppressed the inter diffusion of oxidizing species into the HfO2 films, whereas the bottom Al2O3 layer blocked the outdiffusion of In and P atoms. As a result, the formation of In-O bonds was more effectively suppressed in the Al2O3/HfO2/Al2O3/InP structure than that in the HfO2-on-InP system. Moreover, conductance data revealed that the Al2O3 layer on InP reduces the midgap traps to 2.6 X 10(12) eV(-1) cm(-2) (compared to that of HfO2/InP, that is, 5.4 X 10(12) eV(-1) cm(-2)). The suppression of gap states caused by the outdiffusion of In atoms significantly controls the degradation of capacitors caused by leakage current through the stacked oxide layers.</P>

치과 임플란트용 티타늄 합금의 신회층에 대한 전기화학적 연구

허권봉(Kweon Bong Heo),최기열(Ki Yeol Choi),이중배(Joong Bae Lee) 대한치과재료학회 2010 대한치과재료학회지 Vol.37 No.4

The characteristics of oxide layers formed on cp-Ti, T16A14V ELI alloy, and Ti6A17Nb alloy were studied. The basic corrosion resistance was estimated by static immersion test, and the passivation behavior was studied by several electrochemical techniques; open circuit potential vs, time measurement, potentiodynamic polarization, potentiostatic current vs. time measurement, and electrochemical impedance spectroscopy (EIS). The polarization resistance of oxide layer was calculated by fitting the EIS data to the equivalent circuit model. The strong passivation was observed for all three materials. Only negligible amounts of metals were dissolved during the static immersion test, and the passive currents less than a few tens of μ A/㎠ were recorded over a wide range of anodic potential in the electrochemical test. The typical shape of fast passivation was seen in the open circuit potential vs. time curves. The EIS data for three materials was fitted to the equivalent circuit model R(QR). Ti6Al4V ELI alloy showed the highest passivation rate among three materials at the initial stage of oxidation. However, the passivation was deteriorated in the electrochemical oxidation condition and also in acid solution, probably due to the damage of oxide layer, then the polarization resistance rapidly decreased. On the other hand, the passivation of pure titanium was stabilized in the electrochemical oxidation condition by thickening of oxide layer. Ti6Al7Nb alloy showed the lowest passivation rate among three materials in all conditions.

치과 임플란트용 티타늄 합금의 산화층에 대한 전기화학적 연구

허권봉,최기열,이중배 대한치과재료학회 2010 대한치과재료학회지 Vol.37 No.4

The characteristics of oxide layers formed on cp-Ti, Ti6Al4V ELI alloy, and Ti6Al7Nb alloy were studied. The basic corrosion resistance was estimated by static immersion test, and the passivation behavior was studied by several electrochemical techniques; open circuit potential vs. time measurement, potentiodynamic polarization,potentiostatic current vs. time measurement, and electrochemical impedance spectroscopy (EIS). The polarization resistance of oxide layer was calculated by fitting the EIS data to the equivalent circuit model. The strong passivation was observed for all three materials. Only negligible amounts of metals were dissolved during the static immersion test, and the passive currents less than a few tens of μA/cm2 were recorded over a wide range of anodic potential in the electrochemical test. The typical shape of fast passivation was seen in the open circuit potential vs. time curves. The EIS data for three materials was fitted to the equivalent circuit model R(QR). Ti6Al4V ELI alloy showed the highest passivation rate among three materials at the initial stage of oxidation. However, the passivation was deteriorated in the electrochemical oxidation condition and also in acid solution,probably due to the damage of oxide layer, then the polarization resistance rapidly decreased. On the other hand,the passivation of pure titanium was stabilized in the electrochemical oxidation condition by thickening of oxide layer. Ti6Al7Nb alloy showed the lowest passivation rate among three materials in all conditions.

Formation of a functional homo-junction interface through ZnO atomic layer passivation: Enhancement of carrier mobility and threshold voltage in a ZnO nanocrystal field effect transistor

Kim, Youngjun,Chang, Mincheol,Cho, Seongeun,Kim, Minkyong,Kim, Hyunsik,Choi, Eunsoo,Ko, Hyungduk,Hwang, Jinha,Park, Byoungnam Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.804 No.-

<P><B>Abstract</B></P> <P>We report enhancement of mobility and increase in mobile carrier concentration in zinc oxide (ZnO) nanocrystal (NC) field effect transistors (FETs) through the formation of a homo-junction interface using atomic layer deposition (ALD) passivation. An ultrathin ALD-ZnO passivation film deposited on a ZnO NC film not only increased the FET mobility from 4.6ⅹ10<SUP>−6</SUP> to 1.4ⅹ10<SUP>−4</SUP> cm<SUP>2</SUP>/V but also caused earlier turn-on of the ZnO NC FETs, shifting the threshold voltage from 18.9 to −4.6 V. The enhanced FET mobility and earlier turn-on in the FET are attributed to reduced localized state density on the ZnO NC surface through ALD-ZnO passivation. Passivation of the surface states mitigates carrier depletion in the ZnO NC film through oxygen adsorption on the ZnO surface. We also observed that the presence of saturation of the drain in a high drain-source voltage region depends on the ALD-ZnO passivation and its origin is discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We formed a ZnO-NC/ZnO-ALD planar-homojunction interface, passivating the surface. </LI> <LI> Carrier mobility in the accumulation layer was enhanced by surface passivation. </LI> <LI> Suppression of surface depletion by ALD are crucial in assembling devices. </LI> </UL> </P>

CsCl 보호막을 이용한 전면발광 OLED의 전기 및 광학적 특성

김소연,문대규,한정인,Kim, So-Youn,Moon, Dae-Gyu,Han, Jeong-In 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.2

We have developed the transparent passivation layer for top emission organic light emitting diodes using CsCl thin film by the thermal evaporation method. The CsCl film was deposited on the Ca/Ag semitransparent cathode. The optical transmittance of Ca/ Ag/CsCl triple layer is higher than that of Ca/Ag double layer in the visible range. The device with a structure of glass/Ni/2-TNATA/a-NPD/Alq3:C545T/BCP/Alq3/Ca/Ag/CsCl results in higher efficiency than the device without CsCl passivation layer. The device without CsCl thin film shows a current efficiency of 7 cd/A, whereas the device passivated with CsCl layer shows an efficiency of 10 cd/A. This increase of efficiency isresulted from the increased optical extraction by the CsCl passivation layer.

결정질 실리콘 태양전지의 Al<SUB>2</SUB>O<SUB>3</SUB>/SiN<SUB>X</SUB> 패시베이션 특성 분석

현지연(Ji Yeon Hyun),송인설(In Seol Song),김재은(Jae Eun Kim),배수현(Soohyun Bae),강윤묵(Yoonmook Kang),이해석(Hae-Seok Lee),김동환(Donghwan Kim) 한국태양광발전학회 2017 Current Photovoltaic Research Vol.5 No.2

Aluminum oxide (Al2O3) film deposited by atomic layer deposition (ALD) is known to supply excellent surface passivation properties on crystalline Si surface. The quality of passivation layer is important for high-efficiency silicon solar cell. double-layer structures have many advantages over single-layer materials. Al2O3/SiNX passivation stacks have been widely adopted for high- efficiency silicon solar cells. The first layer, Al2O3, passivates the surface, while SiNX acts as a hydrogen source that saturates silicon dangling bonds during annealing treatment. We explored the properties on passivation film of Al2O3/SiNX stack layer with changing the conditions. For the post annealing temperature, it was found that 500 ℃ is the most suitable temperature to improvement surface passivation.