Highly Flexible Dye-sensitized Solar Cell Prepared on Single Metal Mesh

Yun, Min Ju,Cha, Seung I.,Seo, Seon Hee,Lee, Dong Y. Korea Photovoltaic Society 2014 Current Photovoltaic Research Vol.2 No.3

Dye-sensitized solar cells (DSSCs) are applied in the emerging fields of building integrated photovoltaic and electronics integrated photovoltaic like small portable power sources as demands are increased with characteristic advantages. Highly flexible dye-sensitized solar cells (DSSCs) prepared on single stainless steel mesh were proposed in this paper. Single mesh DSSCs structure utilizing the spraying the chopped glass paper on the surface treated stainless steel mesh for integrating the space element and the electrode components, counter electrode component and photoelectrode component were coated on each side of the single mesh. The fabricated single mesh DSSCs showed the energy-conversion efficiency 0.50% which show highly bendable ability. The new single mesh DSSCs may have potential applications as highly bendable solar cells to overcome the limitations of TCO-based DSSCs.

Industry Applicable Future Texturing Process for Diamond wire sawed Multi-crystalline Silicon Solar Cells: A review

Ju, Minkyu,Lee, Youn-Jung,Balaji, Nagarajan,Cho, Young Hyun,Yi, Junsin Korea Photovoltaic Society 2018 Current Photovoltaic Research Vol.6 No.1

Current major photovoltaic (PV) market share (> 60%) is being occupied by the multicrystalline (mc)-silicon solar cells despite of low efficiency compared to single crystalline silicon solar cells. The diamond wire sawing technology reduces the production cost of crystalline silicon solar cells, it increases the optical loss for the existing mc-silicon solar cells and hence its efficiency is low in the current mass production line. To overcome the optical loss in the mc-crystalline silicon, caused by the diamond wire sawing, next generation texturing process is being investigated by various research groups for the PV industry. In this review, the limitation of surface structure and optical loss due to the reflectivity of conventional mc-silicon solar cells are explained by the typical texturing mechanism. Various texturing technologies that could minimize the optical loss of mc-silicon solar cells are explained. Finally, next generation texturing technology to survive in the fierce cost competition of photovoltaic market is discussed.

Preparation and Properties of ZnSe/Zn₃P₂ Heterojunction Formed by Surface Selenization of Zn₃P₂ Film Deposited on ZnTe Layer

Park, Kyu Charn,Cha, Eun Seok,Shin, Dong Hyeop,Ahn, Byung Tae,Kwon, HyukSang Korea Photovoltaic Society 2014 Current Photovoltaic Research Vol.2 No.1

ZnSe/$Zn_3P_2$ heterojunctions with a substrate configuration were fabricated using a series of cost-effective processes. Thin films of ZnTe and $Zn_3P_2$ were successively grown by close-spaced sublimation onto Mo-coated glass substrates. ZnSe layers thinner than 100nm were formed by annealing the $Zn_3P_2$ films in selenium vapor. Surface selenization generated a high density of micro-cracks which, along with voids, provided shunt paths and severely deteriorated the diode characteristics. Annealing the $Zn_3P_2$ film at $300^{\circ}C$ in a $ZnCl_2$ atmosphere before surface selenization produced a dense microstructure and prevented micro-crack generation. The mechanism of micro-crack generation by the selenization was described and the suppression effect of $ZnCl_2$ treatment on the micro-crack generation was explained. ZnSe/$Zn_3P_2$ heterojunctions with low leakage current ($J_0$ < $1{\mu}A/cm^2$) were obtained using an optimized surface selenization process with $ZnCl_2$ treatment. However, the series resistance was very high due to the presence of an electrical barrier between the ZnTe and $Zn_3P_2$ layers.

Advances in High Efficiency Back Contact Back Junction Solar Cells

Balaji, Nagarajan,Park, Cheolmin,Raja, Jayapal,Yi, Junsin Korea Photovoltaic Society 2015 Current Photovoltaic Research Vol.3 No.2

In the past few decade's researchers, scientists, engineers of photovoltaic (PV) industry are working towards low cost high efficiency Si solar cells. Over the last decade the interest in back contact solar cell has been acquiring as well as a gradual introduction to industrial applications is increasing. As an alternative to conventional solar cells with a front and rear contact, the back-contact cells has remained a research topic. The aim of this work is to present a comprehensive summary of results incurred in the back contact back junction solar cells such as interdigitated back-contact (IBC), emitter wrap-through (EWT) and metallization wrap-through (MWT) over the years.

Effect of Se Flux and Se Treatment on the Photovoltaic Performance of β-CIGS Solar Cells

Kim, Ji Hye,Cha, Eun Seok,Park, Byong Guk,Ahn, Byung Tae Korea Photovoltaic Society 2015 Current Photovoltaic Research Vol.3 No.2

$Cu(In,Ga)_3Se_5$ (${\beta}-CIGS$) has a band gap of 1.35 eV which is an optimum value for high solar-energy conversion efficiency. However, ${\beta}-CIGS$ film was not well characterized yet due to lower efficiency compared to $Cu(In,Ga)Se_2$ (${\alpha}-CIGS$). In this work, ${\beta}-CIGS$ films were fabricated by a three-stage co-evaporation of elemental sources with various Se fluxes. As the Se flux increased, the crystallinity of ${\beta}-CIGS$ phase was improved from the analysis of Raman spectroscopy and a deep-level defect was reduced from the analysis of photoluminescence spectroscopy. A Se treatment of the ${\beta}-CIGS$ film at $200^{\circ}C$ increased Ga content and decreased Cu content at the surface of the film. With the Se treatment at $200^{\circ}C$, the cell efficiency was greatly improved for the CIGS films prepared with low Se flux due to the increase of short-circuit current and fill factor. It was found that the main reason of performance improvement was lower Cu content at the surface instead of higher Ga content.

Feasibility of Indium Tin Oxide (ITO) Swarf Particles to Transparent Conductive Oxide (TCO)

Hong, Sung-Jei,Yang, DuckJoo,Cha, Seung Jae,Lee, Jae-Yong,Han, Jeong-In Korea Photovoltaic Society 2015 Current Photovoltaic Research Vol.3 No.2

Indium (In) is widely used for transparent electrodes of photovoltaics as a form of indium tin oxide (ITO) due to its superior characteristics of environmental stability, relatively low electrical resistivity and high transparency to visible light. However, In has been worn off in proportion to growth the In related market, and it leads to raise of price. Although In is obtained from ITO target scarps, much harmful elements are used for the recycling process. To decrease of harmful elements, ITO swarf particles obtained from target scraps was characterized whether it is feasible to transparent conductive oxide (TCO). The ITO swarf was crushed with milling process, and it was mixed with new ITO nanoparticles. The mixed particles were well dispersed into ink solvent to make-up an ink, and it was well coated onto glass substrate. After heat-treatment at $400^{\circ}C$ under $N_2$ rich environments, optical transmittance at 550 nm and sheet resistance of the ITO ink coated layer was 71.6% and $524.67{\Omega}/{\square}$, respectively. Therefore, it was concluded that the ITO swarf was feasible to TCO of touch screen panel.

Poling Field Effect on Absorption and Luminescence of Disperse Red-19 and TiO₂ Composites

Kim, Byoung-Ju,Hwang, Un-Jei,Jo, Dong-Hyun,Lim, Sae-Han,Kang, Kwang-Sun Korea Photovoltaic Society 2015 Current Photovoltaic Research Vol.3 No.1

Absorption and luminescence characteristics of disperse red-19 (DR-19) and $TiO_2$ composite have been investigated with various poling electric field strengths. Two step synthetic processes were employed to employ the DR-19 to the $TiO_2$ sol-gel. Firstly, urethane bond formation between DR-19 (-OH) and 3-isocyanatopropyl triethoxysilane (ICPTES, -N=C=O) performed (ICPDR) prior incorporation to the $TiO_2$ sol-gel. Secondary, the hydrolysis of the ethoxy group from the ICPTES and condensation reaction between silanol groups from ICPTES and $TiO_2$ sol-gel were performed. The ICPDR and $TiO_2$ sol-gel ($DRTiO_2$) were mixed and stirred for several days. The composite was coated to the ITO coated glass substrate. Corona poling were performed before drying the composite with various electric field strengths. The absorption intensity decreased with the increase of the poling field strength, which resulted in the increase of poling efficiency. The photoluminescence also decreased as the poling field strength increased. There is long luminescence tail for the poled $DRTiO_2$ film compared with unpoled $DRTiO_2$ film. The luminescence long tail indicates that the self-trapped excitons and polarons were generated when the $DRTiO_2$ film was poled with electric field.

Quadrant Analysis in Correlation between Mechanical and Electrical Properties of Low-Temperature Conductive Film Bonded Crystalline Silicon Solar Cells

Baek, Su-Wung,Choi, Kwang-Il,Lee, Woo-Hyoung,Lee, Suk-Ho,Cheon, Chan-Hyuk,Hong, Seung-Min,Lee, Kil-Song,Shin, Hyun-Woo,Yan, Yeon-Won,Lim, Cheolhyun Korea Photovoltaic Society 2015 Current Photovoltaic Research Vol.3 No.1

In this study, we analyzed the correlation between mechanical and electrical properties of low-temperature conductive film (LT-CF) bonded silicon solar cells by a quadrant analysis (horizontal axis (peeling strength), vertical axis (power loss)). We found that a series of points with various bonding parameters such as bonding temperature, pressure and time were distributed in the different three regimes; weak regime (Q2: weak bonding strength and high power loss), moderate regime (Q4 : strong bonding strength and low power loss) and hard regime (Q3 : weak bonding strength and low power loss). Using this analogous technique, it was possible to fabricate the LT-CF bonded silicon solar cells with the various conditions displayed in Q3 of the quadrant plots, possessing the peeling strength of ~ 1N/mm and power loss of 2~3%.

Luminescent Properties of LaBO₃:RE³⁺ (RE=Tb, Ce) Phosphors for White Light Emitting Diodes

Cho, Shinho Korea Photovoltaic Society 2014 Current Photovoltaic Research Vol.2 No.2

$Tb^{3+}$ - or $Ce^{3+}$-doped $LaBO_3$ phosphors were synthesized by a solid-state reaction process with different concentrations of activator ions. The XRD spectra showed the monoclinic $LaBO_3$ pattern with the main peak occurring at (014) plane, irrespective of the kind of activator ions. The crystallite size was determined by using the Scherrer formula, and the maximum was obtained with an activator concentration of 0.05 mol for both phosphors. The emission spectra of $LaBO_3$ phosphors doped with $Tb^{3+}$ ions under excitation at 269 nm exhibited three major emission bands at 488, 544, and 587 nm. The strongest emission was green at 544 nm owing to the $^5D_4-^7F_5$ transition at a $Tb^{3+}$ ion concentration of 0.05 mol. For the $Ce^{3+}$-doped $LaBO_3$ phosphors, one strong blue band centered at 469 nm and weak multipeaks were observed. These results suggest that the optimum green and blue emission can be realized by controlling the concentration and type of activator ions incorporated in the host crystal.

Present Status and Prospects of Thin Film Silicon Solar Cells

Iftiquar, Sk Md,Park, Jinjoo,Shin, Jonghoon,Jung, Junhee,Bong, Sungjae,Dao, Vinh Ai,Yi, Junsin Korea Photovoltaic Society 2014 Current Photovoltaic Research Vol.2 No.2

Extensive investigation on silicon based thin film reveals a wide range of film characteristics, from low optical gap to high optical gap, from amorphous to micro-crystalline silicon etc. Fabrication of single junction, tandem and triple junction solar cell with suitable materials, indicate that fabrication of solar cell of a relatively moderate efficiency is possible with a better light induced stability. Due to these investigations, various competing materials like wide band gap silicon carbide and silicon oxide, low band gap micro-crystalline silicon and silicon germanium etc were also prepared and applied to the solar cells. Such a multi-junction solar cell can be a technologically promising photo-voltaic device, as the external quantum efficiency of such a cell covers a wider spectral range.