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In this study, we investigated the microstructures, hydrogen absorption kinetics, and surface oxides of a Ti0.2Zr0.2Nb0.2V0.2Cr0.17Fe0.03 high entropy alloy (HEA). The prepared HEA had a dual phase microstructure consisting of body-centered cubic (BCC) phase (32.2Ti-13.1Zr-30.3Nb-18.6 V-5.8Cr) and face-centered cubic (FCC) phase (11.3Ti-19.6Zr-13.2Nb-24.7 V-25.7Cr-5.5Fe). The HEA ingot absorbed hydrogen under a hydrogen pressure of 5 bar at room temperature without any thermal activation process. After hydrogenation, the FCC and BCC phases were transformed to a monohydride and a dihydride phase, respectively. To examine the hydrogen absorption behavior of each phase, two ingots having the same compositions as the BCC and the FCC phases were separately prepared. Though the BCC phase ingot did not react with hydrogen, the FCC phase ingot absorbed hydrogen, which could result from the formation of a highly reactive oxide layer on the FCC phase ingot. From the X-ray photoelectron spectroscopy results of the two ingots, although the BCC phase ingot contained Cr, no Cr was detected in the oxide layer. In contrast, the oxide layer on the FCC phase ingot displayed a high Cr concentration, and it seems that the reactivity of the oxide layer with hydrogen could be improved by the presence of Cr in the surface oxides.

The silicon surface texture significantly affects the current density and efficiency of perovskite/silicon tandem solar cells. However, only a few studies have explored fabricating perovskite on textured silicon and the effect of texture on perovskite films because of the limitations of solution processes. Here we produce conformal perovskite on textured silicon with a dry two-step conversion process that incorporates lead oxide sputtering and direct contact with methyl ammonium iodide. To separately analyze the influence of each texture structure on perovskite films, patterned texture, high-resolution photoluminescence (μ-PL), and light beam-induced current (μ-LBIC), 3D mapping is used. This work elucidates conformal perovskite on textured surfaces and shows the effects of textured silicon on the perovskite layers with high-resolution 3D mapping. This approach can potentially be applied to any type of layer on any type of substrate. The efficiency of perovskite/silicon tandem solar cells is affected by silicon surface texture, however fabrication processes in solution limit surface studies. Here a perovskite layer on textured silicon is formed through a dry two-step conversion process with lead oxide sputtering and direct contact with methyl ammonium iodide.

Radio frequency (RF) magnetron-sputtered TiO2 (RS-TiO2) is investigated as a hole-blocking layer for perovskite solar cells. RS-TiO2 shows conformal, dense, and efficiently electron transferable pr...

We investigated strontium oxide (SrO) as an interlayer material to enhance the UV stability of a CH3NH3PbI3 perovskite solar cell. Moisture and over 400 nm wavelength of light were excluded to investigate the effect of UV light only. Two different interlayer fabrication processes were examined to optimize the performance of this solar cell. Devices fabricated by dipping for 30 min in SrO solution exhibited photoconversion efficiencies of 15.5%, whereas those fabricated with 60-min dipping showed photoconversion efficiencies of 15% and exhibited local Sr agglomeration. Devices with SrO displayed lower initial efficiencies than those without any SrO layer (17.6%), However, a device without SrO retained only 34.4% of its initial efficiency after 100 h of UV exposure. In contrast, SrO-incorporated devices retained almost 60.0% of their initial efficiency. Severe μ-PL mapping intensity degradation was observed in devices that did not include the interlayer, but no degradation was observed in those with the SrO interlayer. This can be attributed to the passivation of the degradation sites by SrO.

Correction to: Communications Chemistry https://doi.org/10.1038/s42004-020-0283-4, published online 25 March 2020. The original version of this Article incorrectly designated Yoonmook Kang as a corresponding author and listed their e-mail address in error. This has now been corrected in the PDF and HTML versions of the Article.

Organic–inorganic halide Perovskite solar cells have extremely high power conversion efficiencies of 22.1%, as officially recognized by the US National Renewable Energy Laboratory (NREL). These solar cells are therefore attractive candidates for use in next generation photovoltaic applications. Perovskite materials for incorporation into solar cells are prepared by a two-step solution fabrication process to generate polycrystalline structures with diverse grain sizes. PbI2 is the main material used in the synthesis of organic–inorganic hybrid perovskite, particularly when the sequential deposition method is employed, as it facilitates the formation of a well-organized perovskite layer. To improve the performance of these devices, the properties of PbI2 properties need to be investigated. We therefore examined the effects of PbI2 concentration in mesoporous perovskite solar cells prepared using a two-step solution deposition method. Samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis spectrometry, and atomic force microscopy (AFM). The results of this work confirm the importance of the PbI2 layer in high efficiency perovskite solar cells.

Passivated contact in advanced high-efficiency silicon solar cells based on the full back surface field (BSF) is reported here in based on the application of a tunnel oxide layer that is less than 2 nm thick. The open-circuit voltage ( V oc ) was significantly improved via interface passivation due to insertion of the tunnel oxide layer. During oxide layer growth, a transition region, such as a sub-oxide, was observed at a depth of about 0.75 nm in the growth interface between the silicon oxide layer and silicon substrate. The properties of the less than 2 nm thick tunnel oxide layer were primarily affected by the characteristics of the transition region. The passivation characteristics of tunnel oxide layer should depend on the physical properties of the oxide. The interface trap density D it is an important parameter in passivation and is influenced by the stoichiometry of the oxide which in turn strongly affected by the fabrication and the post annealing conditions. During heat treatment of a-Si:H thin films (for the purpose of crystallization to form doped layers), thin film blistering occurs due to hydrogen effusion on flat substrate surfaces. To minimize this behavior, we seek to control the surface morphology and annealing profile. Also, the passivation quality of passivataed contact structure declined for the sample annealed above 900 °C. This decline was attributed not only to local disruption of the tunnel oxide layer, but also to phosphorus diffusion. The resistivity of the tunnel oxide layer declined precipitously for the sample annealed above 900 °C. On the basis of these, implied V oc over 740 mV was achieved in n-type Si wafer through the control of the oxide stoichiometry via optimizing the annealing conditions.

Hydrogenated silicon nitride (SiNx:H) films were fabricated using plasma-enhanced chemical vapor deposition at high (13.56 MHz), low (400 kHz), and dual (13.56 MHz + 400 kHz) radio frequencies. The antireflection and passivation qualities of each film were investigated before their application as the front surface layer of crystalline silicon solar cells. The use of a high radio frequency was observed to have a positive effect on the cell performance, which increased by 0.4% in comparison with the minimum value obtained for a 156 mm × 156 mm cell.

In this study, we employ a combination of various in-situ surface analysis techniques to investigate the thermally induced degradation processes in MAPbI3 perovskite solar cells (PeSCs) as a function of temperature under air-free conditions (no moisture and oxygen). Through a comprehensive approach that combines in-situ grazing-incidence wide-angle X-ray diffraction (GIWAXD) and high-resolution X-ray photoelectron spectroscopy (HR-XPS) measurements, we confirm that the surface structure of MAPbI3 perovskite film changes to an intermediate phase and decomposes to CH3I, NH3, and PbI2 after both a short (20 min) exposure to heat stress at 100 °C and a long exposure (>1 hour) at 80 °C. Moreover, we observe clearly the changes in the orientation of CH3NH3+ organic cations with respect to the substrate in the intermediate phase, which might be linked directly to the thermal degradation processes in MAPbI3 perovskites. These results provide important progress towards improved understanding of the thermal degradation mechanisms in perovskite materials and will facilitate improvements in the design and fabrication of perovskite solar cells with better thermal stability.

Silicon oxynitride (SiON) could be used in combination with silicon nitride (SiN) to form a multilayer anti-reflection coating on the front side of selective emitter solar cells. In this study, these double anti-reflection layers were fabricated by a continuous deposition technique using the plasma enhanced chemical vapor deposition method. We attempted to determine whether this method is fast and cost effective and can achieve higher efficiency for solar cell manufacture. The results show that the short circuit current density for the double layer anti-reflection coating on selective emitter solar cells was higher by 0.5 mA/cm2 compared to the single layer coating owing to the improved optical reflectance. The incorporation of a SiN/SiON stack into the anti-reflection layer of the CZ selective emitter solar cells yields an energy conversion efficiency of 19.4%, which is higher than the efficiency (19.18%) for the reference solar cells with single layer SiN anti-reflection coating.

Organic-inorganic hybrid perovskite solar cells (PSCs) have been extensively studied because of their outstanding performance: a power conversion efficiency exceeding 22% has been achieved. The most commonly used PSCs consist of CH3NH3PbI3 (MAPbI3) with a hole-selective contact, such as 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spiro-bifluorene (spiro-OMeTAD), for collecting holes. From the perspective of long-term operation of solar cells, the cell performance and constituent layers (MAPbI3, spiro-OMeTAD, etc.) may be influenced by external conditions like temperature, light, etc. Herein, we report the effects of temperature on spiro-OMeTAD and the interface between MAPbI3 and spiro-OMeTAD in a solar cell. It was confirmed that, at high temperatures (85 °C), I− and CH3NH3+ (MA+) diffused into the spiro-OMeTAD layer in the form of CH3NH3I (MAI). The diffused I− ions prevented oxidation of spiro-OMeTAD, thereby degrading the electrical properties of spiro-OMeTAD. Since ion diffusion can occur during outdoor operation, the structural design of PSCs must be considered to achieve long-term stability.

In conventional sequential deposition, PbI 2 -free CH 3 NH 3 PbI 3 perovskite films can be achieved when the PbI 2 substrate reacts with a relatively low-concentration CH 3 NH 3 I solution ( 3 NH 3 I per 1 mL of IPA) but the film that is formed has only sparse and uneven coverage. On the other hand, a dense CH 3 NH 3 PbI 3 perovskite film can be formed on a mesoporous TiO 2 substrate when the PbI 2 substrate reacts with a relatively high-concentration MAI solution (>8 mg of CH 3 NH 3 I per 1 mL of IPA), but unreacted PbI 2 is still present in CH 3 NH 3 PbI 3 layer in such cases. Here, we developed organic-inorganic perovskite solar cells with high efficiency by preparing dense and PbI 2 -free films using a modified sequential deposition process. By utilizing the reaction behavior between PbI 2 and MAI, solar cells with an average power-conversion efficiency of 15.1% and high reproducibility and stability were achieved.

Fabricating perovskite on textured silicon surface is important for maximizing current density and the power conversion efficiency (PCE) of perovskite/silicon tandem solar cells. However, producing conformal perovskite on textured silicon surface is difficult because most of high efficiency perovskite solar cells have been produced by solution based process. Herein, we investigated possibility of producing perovskite solar cells on textured silicon surface by dry two-step conversion process and analyzing them with periodically patterned texture and photoluminescence mapping. Thickness scale difference between perovskite and silicon substrate have induced focusing problems.

In this study, perovskite thin films (PFs) were conformally deposited on 100 cm2 textured silicon substrates using a two-step vacuum process. The PFs were fabricated by converting thin films of a sputtered-PbO precursor using the chemical vapor deposition process. The conversion of PbO thin films into PFs was confirmed by X-ray diffractometry. The uniformity of reflectance and thickness was higher than 86% and 92%, respectively, on 100 cm2 textured substrate. We appliedmethylammoniumvapor treatment for complete conversion without residual layer and the power conversion efficiency was 10.2% on a glass/FTO/TiO2/MAPbI3/Spiro-MeOTAD/Au structure.

Sol–gel derived nano-sized glass frits were incorporated into the Ag conductive ink for silicon solar cell metallization. This mixture was specifically formulated for inkjet printing on textured Si wafers with 80 nm thick SiNx anti reflection coating layers. The correlation between the contact resistance and interface microstructures were studied using scanning electron microscopy and transmission electron microscopy. In addition, the specific contact resistance between the front contact and emitter was measured at various firing conditions using the transfer length model. On an emitter with the sheet resistance of 60 Ω/sq, a specific contact resistance below 5 mΩ cm2 could be achieved at a peak firing temperature around 800 °C. We found that the incorporated nano-glass frit act as a very effective fire through agent, and an abundant amount of Ag crystallites was observed along the interface glass layer. (© 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)

BACKGROUND: The prognostic significance of change in red cell distribution width (RDW) during hospital stays in patients treated with therapeutic hypothermia (TH) after out-of-hospital cardiac arrest (OHCA) was investigated. METHODS: Patients treated with TH after OHCA between January 2009 and August 2013 were reviewed. Patients with return of spontaneous circulation (ROSC) were assessed according to Utstein Style. Hematologic variables including RDW, hematocrit, white blood cell count, and platelets were also obtained. RDW changes during the 72 hours after ROSC were categorized into five groups as follows: Group 1 (-0.8-0.1%), Group 2 (0.2-0.3%), Group 3 (0.4-0.5%), Group 4 (0.6-0.8%), and Group 5 (>0.8%). RESULTS: A total of 218 patients were enrolled in the study. RDW changes during the 72 hours after ROSC in Group 4 (HR 3.56, 95% CI 1.25-10.20) and Group 5 (HR 5.07, 95% CI 1.73-14.89) were associated with a statistically significant difference in one-month mortality. RDW changes were associated with statistically significant differences in neurologic outcome at 6 months after ROSC (Group 3 [HR 2.45, 95% CI 1.17-5.14], Group 4 [HR 2.79, 95% CI 1.33-5.84], Group 5 [HR 3.50, 95% CI 1.35-7.41]). Other significant variables were location of arrest, cause of arrest, serum albumin, and advanced cardiac life support time. CONCLUSIONS: RDW change during the 72 hours after ROSC is a predictor of mortality and neurologic outcome in patients treated with TH after OHCA.

N-type silicon-based solar cells are currently being used for achieving high efficiency. However, most of the photovoltaic modules already constructed are based on p-type silicon solar cells, and there are few studies on potential induced degradation (PID) in n-type solar cells. In this study, we investigated PID in n-type silicon solar cells with a front p+ emitter. Further, the PID characteristics of n-type solar cells are compared with those of p-type solar cells. The electrical properties of PID in solar cells are observed with the light I-V, quantum efficiency (QE), and electroluminescence (EL). The possible causes for the change in the external quantum efficiency (EQE) after PID are interpreted using PC1D and are discussed by comparing the experimental results with the simulation results.

Lower performance of multi-crystalline silicon solar cells is usually observed after long-term damp heat test at 85 °C/85% relative humidity. Performance degradation is known to result from the loss in fill factor (FF) due to high series resistance. The causes of the increase in the series resistance are the reduction of the photovoltaic (PV) ribbon in the solder joint and the oxidation of surface on the front Ag finger by high thermal and moisture stress. Additionally, severe degradation by FF loss after damp heat originated from the contact resistance between Si and Ag fingers. Ag crystallites on Si wafer and bulk Ag at the edge of the Ag finger were partially oxidized and could not play a role in the current path of photo-generated electrons.

A boron-rich layer (BRL) is formed during the boron diffusion process in fabricating crystalline Si solar cells. We investigated the structural, optical, and electrical characteristics of BRL in n-type silicon. A boron emitter was formed using the BBr 3 liquid source in a tube furnace at 950 °C. BRL had an amorphous phase. The peak concentration of boron in BRL was over 10 23 atoms/cm 3 . BRL consisted of boron, silicon, and oxygen. The oxygen atoms seemed to have caused the formation of amorphous phase. BRL showed the refractive indices of 1.5–2.0, and the contact resistance of 0.8 mΩ cm 2 .

Photovoltaic (PV) modules have been in use for more than 25 years. The gradual degradation of PV modules is determined by its components and the solar cells. We analyzed the long-term reliability of solar cells using a 25-year-old field-aged PV module. The power of a large size PV module was reduced by approximately 24.6% owing to the delamination of two specific solar cell portions. For a single cell module from a large size PV module, the decrease of short circuit current (Isc) was caused by the discoloration of the ethylene-vinyl acetate. The maximum power (Pmax) decreased by 11.5% compared with its initial value; however, this is not an effect of the degradation of the solar cell. Despite being manufactured in the 1980s, these solar cells did not fail and have little power loss and excellent durability after 25 years.

For high efficiency silicon solar cells, surface texturing is used to increase the short circuit current by reducing the surface reflection loss. Surface texturing is an anisotropic wet chemical etching process commonly used to form random pyramids. We investigated how the process is affected by surface conditions. We also compared the texturing behavior and cell performances of as-cut, polished and saw-damage etched wafers. Textured samples with different processing times were analyzed to detect pyramids and determine weighted reflectances. After the texturing process, conventional screen-printed solar cells were fabricated to observe the cell performance. The pseudo I – V curves and quantum efficiency for the samples were analyzed. Performance of samples with different surface conditions makes no difference. Thus, the processing-cost of solar cells can be reduced by omitting the saw-damage etching process.

In this study, the influence of HF treatment of Ag pastes after a firing process was investigated. It was shown that the HF treatment can improve the fill factors and efficiencies of various cells including those with high initial specific contact resistances. SEM images showed that this improvement is due to the etching of the thin glass layer at the Ag-Si boundary, which exposes the Ag crystallites and colloids. These colloids electrically connect the bulk Ag to the Si through a direct contact, which reduces both the transfer length and the specific contact resistance. A model of the current path was proposed to explain the effect of HF treatment on the edge of the Ag grid.

We carried out the surface texturing of crystalline silicon in alkaline solutions via anisotropic etching. We achieved random pyramids of about 10 μm in size. The size of these pyramids was then gradually reduced using a new solution. In this paper, we investigate the impact of the size of the pyramids on the emitter properties and the front electrode (Ag) contact. To make small (∼3.5 μm) and large (∼9.0 μm) pyramids, we controlled the texturing time and performed one-sided texturing using a silicon nitride film. We compared the formation and quality of a POCl 3 -diffused n + emitter in a furnace for small and large pyramids by using SEM images and emitter saturation current density ( J 0e ) measured Quasi-Steady-State Photo-Conductance (QSSPC). For a comparison, we carried out to simulated using TCAD simulator software (SILVACO, the Athena module). After metallization, we measured the Ag contact resistance via the transfer length method (TLM). We observed the surface distributions of the Ag crystallites using SEM images. We used light I – V to measure the performance of screen-printed solar cells. The efficiency of the solar cell in the case of the small and that in the case of the large pyramids improved by about 17.4% and 17.0%, respectively. We believe that differences in the emitter uniformity and the front Ag contact resistance resulted from this difference in the cell performance. Solar cells perform better when the pyramids are small.

The Hydrogenated silicon nitride (SiN x :H) using plasma enhanced chemical vapor deposition is widely used in photovoltaic industry as an antireflection coating and passivation layer. In the high temperature firing process, the SiN x :H film should not change the properties for its use as high quality surface layer in crystalline silicon solar cells. For optimizing surface layer in crystalline silicon solar cells, by varying gas mixture ratios (SiH 4 + NH 3 + N 2 , SiH 4 + NH 3 , SiH 4 + N 2 ), the hydrogenated silicon nitride films were analyzed for its antireflection and surface passivation (electrical and chemical) properties. The film deposited with the gas mixture of SiH 4 + NH 3 + N 2 showed the best properties in before and after firing process conditions. The single crystalline silicon solar cells fabricated according to optimized gas mixture condition (SiH 4 + NH 3 + N 2 ) on large area substrate of size 156 mm × 156 mm (Pseudo square) was found to have the conversion efficiency as high as 17.2%. The reason for the high efficiency using SiH 4 + NH 3 + N 2 is because of the good optical transmittance and passivation properties. Optimized hydrogenated silicon nitride surface layer and high efficiency crystalline silicon solar cells fabrication sequence has also been explained in this study.

Perovskite solar cells have great potential for high efficiency generation but are subject to the impact of external environmental conditions such as humidity, UV and sun light, temperature, and electric fields. The long-term stability of perovskite solar cells is an important issue for their commercialization. Various studies on the stability of perovskite solar cells are currently being performed; however, the stability related to electric fields is rarely discussed. Here the electrical stability of perovskite solar cells is studied. Ion migration is confirmed using the temperature-dependent dark current decay. Changes in the power conversion efficiency according to the amount of the external bias are measured in the dark, and a significant drop is observed only at an applied voltage greater than 0.8 V. We demonstrate that perovskite solar cells are stable under an electric field up to the operating voltage.

N-type silicon with aluminum emitters for rear junctions was studied; aluminum back surface fields were replaced with n-type silicon wafers. Aluminum rear emitters for n-type silicon solar cells were studied with various rapid thermal processing conditions. With fast ramping-up and fast cooling, an aluminum rear junction was formed uniformly with low emitter recombination current. The effects of junction quality on solar cell efficiency were investigated.

High efficiency solar cells require good back surface field passivation and high back reflectance in the rear Al region. In module processes, wafer-based solar cell can break through stress during soldering uneven rear aluminum surfaces - a serious problem that affects throughput. This work examined rear surfaces with respect to controllable process factors such as ramping and cooling rates during rapid thermal processing, and the fineness of aluminum powder used in the screen-printed paste. A faster ramp up rate resulted in a uniform temperature gradient between the aluminum and silicon surfaces. As a results, the bumps on the aluminum surface were small and of high density. Fine aluminum metal powder in the paste for screen-printing contact points resulted in large distribution, high density bumps. Bumps formed during cooling in metallization, their sizes and densities were dependent the on uniformity of the aluminum and silicon liquid wetting of the silicon surface.

Graphene quantum dot (GQD) layers were deposited as an energy-down-shift layer on crystalline-silicon solar cell surfaces by kinetic spraying of GQD suspensions. A supersonic air jet was used to accelerate the GQDs onto the surfaces. Here, we report the coating results on a silicon substrate and the GQDs' application as an energy-down-shift layer in crystalline-silicon solar cells, which enhanced the power conversion efficiency (PCE). GQD layers deposited at nozzle scan speeds of 40, 30, 20, and 10 mm/s were evaluated after they were used to fabricate crystalline-silicon solar cells; the results indicate that GQDs play an important role in increasing the optical absorptivity of the cells. The short-circuit current density was enhanced by about 2.94% (0.9 mA/cm(2)) at 30 mm/s. Compared to a reference device without a GQD energy-down-shift layer, the PCE of p-type silicon solar cells was improved by 2.7% (0.4 percentage points).

The effect of peak firing temperature and grid width on the contact properties between Ag metal and silicon (n+ emitter) was investigated for screen-printed silicon solar cells. We confirmed the factors that control the specific contact resistance as follows: (1) the Ag coverage fraction on the silicon surface, d(2) the thickness of the glass layer and (3) the etching depth on the n+ emitter region. The lowest specific contact resistance (8.27 mΩ x cm2) was obtained at the optimum firing temperature (720 degrees C). We also found that the grid width affected the contact quality of Ag paste because the contact width related to the absorbed heat of samples in RTP system. For this reason, when the grid width was further reduced, meaning more heat absorption, more Ag crystallites grew and the glass layer thickened. Light I-V results of a 6-inch silicon solar cell with minimum busbar width were similar to the PC1D simulation results. The efficiency was improved by 0.2% with the reduction of the busbar width.

The growth behavior of Cr ad-layer on W(110) surface was studied with scanning tunneling microscopy. Two-dimensional islands are formed at Cr coverage of ∼0.3 monolayer, suggesting typical homogeneous nucleation. The growth mode undergoes a transition to the formation of organized nano-scale lines at the coverage of >0.5 monolayer. The grown lines are aligned along [111] and [111] directions at room temperature. At an elevated temperature, trenches are formed in a two-dimensional wetting layer with high aspect ratios. Possible microscopic origins for the observed structures are discussed.

P-type and n-type wafers were implanted with phosphorus and boron, respectively, for emitter formation and were annealed subsequently at 950∼1050∘Cfor 30∼90 min for activation. Boron emitters were activated at1000∘Cor higher, while phosphorus emitters were activated at950∘C. QSSPC measurements show that the impliedVocof boron emitters increases about 15 mV and theJ01decreases by deep junction annealing even after the activation due to the reduced recombination in the emitter. However, for phosphorus emitters the impliedVocdecreases from 622 mV to 560 mV and theJ01increases with deep junction annealing. This is due to the abrupt decrease in the bulk lifetime of the p-type wafer itself from 178 μs to 14 μs. PC1D simulation based on these results shows that, for p-type implanted solar cells, increasing the annealing temperature and time abruptly decreases the efficiency (Δηabs=−1.3%), while, for n-type implanted solar cells, deep junction annealing increases the efficiency andVoc, especially (Δηabs=+0.4%) for backside emitter solar cells.

One of electron donors in organic photovoltaics, P3HT nano patterns of diameter 70∼75 nm, height 40∼55 nm and pitch 95∼105 nm were thermally molded on the area of 18 × 26 mm2. They were molded by thermal molding with a nickel stamp as a mold. The nickel stamp was fabricated by nickel electroforming using a well-arrayed anodic aluminum oxide(AAO) as an original template. The study on the nano patterning of P3HT by thermal molding was performed according to the variations of temperature, molding pressure, and processing time.

【To reduce manufacturing costs of crystalline silicon solar cells, silicon wafers have become thinner. In relation to this, the properties of the aluminium-back surface field (Al-BSF) are considered an important factor in solar cell performance. Generally, screen-printing and a rapid thermal process (RTP) are utilized together to form the Al-BSF. This study evaluates Al-BSF formation on a (111) textured back surface compared with a (100) flat back surface with variation of ramp up rates from 18 to $89^{\circ}C$ /s for the RTP annealing conditions. To make different back surface morphologies, one side texturing using a silicon nitride film and double side texturing were carried out. After aluminium screen-printing, Al-BSF formed according to the RTP annealing conditions. A metal etching process in hydrochloric acid solution was carried out to assess the quality of Al-BSF. Saturation currents were calculated by using quasi-steady-state photoconductance. The surface morphologies observed by scanning electron microscopy and a non-contacting optical profiler. Also, sheet resistances and bulk carrier concentration were measured by a 4-point probe and hall measurement system. From the results, a faster ramp up during Al-BSF formation yielded better quality than a slower ramp up process due to temperature uniformity of silicon and the aluminium surface. Also, in the Al-BSF formation process, the (111) textured back surface is significantly affected by the ramp up rates compared with the (100) flat back surface.】