TOPCon太阳电池单面沉积Poly-Si的工艺研究

目前隧穿氧化层钝化接触(TOPCon)电池制造技术越来越成熟,所耗成本不断降低。行业内普遍采用低压化学气相沉积(LPCVD)方式进行双面沉积或单面沉积。单面沉积存在Poly-Si绕镀问题,严重影响电池片转化效率和外观质量,同时正面绕镀层去除难度较大,在用碱溶液去除绕镀层的同时,存在绕镀层去除不彻底或者非绕镀区域P^(+)层被腐蚀的风险,导致P^(+)发射极受损,严重影响电池片外观质量与性能。双面沉积可避免上述问题,但产能减少一半,制造成本增加。本文对单面沉积Poly-Si工艺及绕镀层去除工艺进行研究,在TOPCon电池正面及背面制作了一层合适厚度的氧化层掩膜,搭配合适的清洗工艺、去绕镀清洗工艺,既可有效地去除P^(+)层绕镀的Poly-Si,也可很好地保护正面P^(+)层及背面掺杂Poly-Si层不受破坏,同时可大幅提升产能。

Optical simulation of CsPbI_(3)/TOPCon tandem solar cells with advanced light management

Monolithic perovskite/Si tandem solar cells(TSCs)have experienced rapid development in recent years,demonstrating its potential to exceed the Shockley-Queisser limit of single junction Si solar cells.Unlike typical organic-inorganic hybrid perovskite/silicon heterojunction TSCs,here we propose CsPbI_(3)/TOPCon TSC,which is a promising architecture in consideration of its pleasurable thermal stability and good compatibility with current PERC production lines.The optical performance of CsPbI_(3)/TOPCon TSCs is simulated by the combination of ray-tracing method and transfer matrix method.The light management of the CsPbI_(3)/TOPCon TSC begins with the optimization of the surface texture on Si subcell,indicating that a bifacial inverted pyramid with a small bottom angle of rear-side enables a further minimization of the optical losses.Current matching between the subcells,as well as the parasitic absorption loss from the front transparent conductive oxide,is analyzed and discussed in detail.Finally,an optimized configuration of CsPbI_(3)/TOPCon TSC with a31.78%power conversion efficiency is proposed.This work provides a practical guidance for approaching high-efficiency perovskite/Si TSCs.

Indium–tin oxide films obtained by DC magnetron sputtering for improved Si heterojunction solar cell applications

The indium-tin oxide （ITO） film as the antireflection layer and front electrodes is of key importance to obtaining high efficiency Si heterojunction （HJ） solar cells. To obtain high transmittance and low resistivity ITO films by direct-current （DC） magnetron sputtering, we studied the impacts of the ITO film deposition conditions, such as the oxygen flow rate, pressure, and sputter power, on the electrical and optical properties of the ITO films. ITO films of resistivity of 4 x 10-4 ~.m and average transmittance of 89% in the wavelength range of 380-780 nm were obtained under the optimized conditions： oxygen flow rate of 0.1 sccm, pressure of 0.8 Pa, and sputtering power of 110 W. These ITO films were used to fabricate the single-side HJ solar cell without an intrinsic a-Si：H layer. However, the best HJ solar cell was fabricated with a lower sputtering power of 95 W, which had an efficiency of 11.47%, an open circuit voltage （Voc） of 0.626 V, a filling factor （FF） of 0.50, and a short circuit current density （Jsc） of 36.4 mA/cm2. The decrease in the performance of the solar cell fabricated with high sputtering power of 110 W is attributed to the ion bombardment to the emitter. The Voc was improved to 0.673 V when a 5 nm thick intrinsic a-Si：H layer was inserted between the （p） a-Si：H and （n） c-Si layer. The higher Voc of 0.673 V for the single-side HJ solar cell implies the excellent c-Si surface passivation by a-Si：H.

Composite electron transport layer for efficient N-I-P type monolithic perovskite/silicon tandem solar cells with high open-circuit voltage

Perovskite/silicon tandem solar cells(PSTSCs) have exhibited huge technological potential for breaking the Shockley-Queisser limit of single-junction solar cells. The efficiency of P-I-N type PSTSCs has surpassed the single-junction limit, while the performance of N-I-P type PSTSCs is far below the theoretical value. Here, we developed a composite electron transport layer for N-I-P type monolithic PSTSCs with enhanced open-circuit voltage(VOC) and power conversion efficiency(PCE). Lithium chloride(Li Cl) was added into the tin oxide(SnO_(2)) precursor solution, which simultaneously passivated the defects and increased the electron injection driving force at the electron transfer layer(ETL)/perovskite interface.Eventually, we achieved monolithic PSTSCs with an efficiency of 25.42% and V_(OC) of 1.92 V, which is the highest PCE and VOCin N-I-P type perovskite/Si tandem devices. This work on interface engineering for improving the PCE of monolithic PSTSCs may bring a new hot point about perovskite-based tandem devices.

Sound insulation property of Al-Si closed-cell aluminum foam bare board material

Al-Si closed-cell aluminum foam bare boards of 1 240 mm×1 100 mm with different densities and thicknesses wereprepared by molten body transitional foaming process.The sound reduction index(R)of Al-Si closed-cell aluminum foam bareboards was investigated experimentally under different frequencies(100-4 000 Hz).It is found that sound reduction index(R)issmall under low frequencies,large under high frequencies and is controlled by different mechanisms.The sound insulation propertybasically conforms with the monolayer board sound insulation theory.The sound reduction index(R)increases with the even growthof thickness and density,but its rising trend is tempered.The single number sound reduction indexes(RW)of specimen with thicknessof 20 cm and density of 0.51 g/cm3are 30.8 dB and 33 dB respectively,which demonstrates good sound insulation property forlightmass materials.

Overexpression of pim-3 and protective role in lipopolysaccharide-stimulated hepatic stellate cells

AIM: To investigate pim-3 expression in hepatic stellate cells(HSCs) stimulated by lipopolysaccharide(LPS), and its protective effect on HSCs. METHODS: Rat HSC-T6 cells were stimulated by LPS. The effect of LPS on proliferation and apoptosis of HSC-T6 cells was investigated by methyl thiazoyltetrazolium(MTT) assay and flow cytometry after annexin V-fluorescein isothiocyanate/propidium iodide double staining. pim-3 m RNA and protein were detected by reverse transcriptase polymerase chain reaction and Western blotting at 48 h when HSC-T6 cells were stimulated with 1 μg/m L LPS for 0, 3, 6, 12, 24 and 48 h. The cells without stimulation served as controls. To study the effect of pim-3 kinase on HSC-T6 cells, si-pim3(si RNA against pim-3) was transfected into HSC-T6 cells. HSC-T6 cells were subjected to different treatments, including LPS, si-pim3, or si-pim3 plus LPS, and control cells were untreated. Protein expression of pim-3 was detected at 48 h after treatment, and cell proliferation at 24 and 48 h by MTT assay. Apoptosis was detected by flow cytometry, and confirmed with caspase-3 activity assay.RESULTS: LPS promoted HSC-T6 cell proliferation and protected against apoptosis. Significantly delayed upregulation of pim-3 expression induced by LPSoccurred at 24 and 48 h for m RNA expression(pim-3/β-actin RNA, 24 or 48 h vs 0 h, 0.81 ± 0.20 or 0.78 ± 0.21 vs 0.42 ± 0.13, P < 0.05), and occurred at 12 h and peaked at 24 and 48 h for protein expression(pim-3/GAPDH protein, 12, or 24 or 48 h vs 0 h, 0.68 ± 0.12, 1.47 ± 0.25 or 1.51 ± 0.23 vs 0.34 ± 0.04, P < 0.01). pim-3 protein was ablated by si-pim3 and upregulated by LPS in HSC-T6 cells at 48 h after treatment(pim-3/GAPDH: si-pim3, si-pim3 plus LPS or LPS vs control, 0.11 ± 0.05, 0.12 ± 0.05 or 1.08 ± 0.02 vs 0.39 ± 0.03, P < 0.01). Ablation of pim-3 by si-pim3 in HSC-T6 cells partly abolished proliferation(OD at 24 h, si-pim3 group or si-pim3 plus LPS vs control, 0.2987 ± 0.050 or 0.4063 ± 0.051 vs 0.5267 ± 0.030, P < 0.01; at 48 h 0.4634 ± 0.056 or 0.5433 ± 0.031 vs 0.8435 ± 0.028, P < 0.01; si-pim3 group vs si-pim3 plus LPS, P < 0.01 at 24 h and P < 0.05 at 48 h), and overexpression of pim-3 in the LPS group increased cell proliferation(OD: LPS vs control, at 24 h, 0.7435 ± 0.028 vs 0.5267 ± 0.030, P < 0.01; at 48 h, 1.2136 ± 0.048 vs 0.8435 ± 0.028, P < 0.01). Ablation of pim3 with si-pim3 in HSC-T6 cells aggravated apoptosis(si-pim3 or si-pim3 plus LPS vs control, 42.3% ±1.1% or 40.6% ± 1.3% vs 16.8% ± 3.3%, P < 0.01; si-pim3 vs si-pim3 plus LPS, P > 0.05), and overexpression of pim-3 in the LPS group attenuated apoptosis(LPS vs control, 7.32% ± 2.1% vs 16.8% ± 3.3%, P < 0.05). These results were confirmed by caspase-3 activity assay.CONCLUSION: Overexpression of pim-3 plays a protective role in LPS-stimulated HSC-T6 cells.

Tensile property of Al-Si closed-cell aluminum foam

Al-Si closed-cell aluminum foams of different densities were prepared by molten body transitional foaming process.The tensile behavior of Al-Si closed-cell aluminum foam was studied and the influence of relative densities on the tensile strength and elastic modulus was also researched.The results show that the fracture surfaces of Al-Si closed-cell aluminum foam display quasi-cleavage fracture consisting of brittle cleavages and ductile dimples.The tensile strength and elastic modulus are strictly affected by the relative density of Al-Si closed-cell aluminum foam.With increasing relative density,the tensile strength increases and the strain at which the peak strength is measured also increases;in addition,the elastic modulus increases with increasing relative density.

Loss Analysis of High-Efficiency Perovskite/Si Tandem Solar Cells for Large Market Applications

The Si tandem solar cells composes of III-V, II-VI, chalcogenide and perovskite top cells and Si bottom cells are very attractive for creation of new markets. The perovskite/Si tandem solar cells are thought to be one of the most promising PV devices because of high-efficiency and low-cost potential. However, efficiencies of perovskite/Si tandem solar cells with an efficiency of 29.8% are lower compared to 39.5% with III-V 3-junction tandem solar cells and 35.9% with III-V/Si 3-junction tandem solar cells. Therefore, it is necessary to clarify and reduce several losses of perovskite/Si tandem solar cells. This paper presents high efficiency potential of perovskite/Si tandem solar cells analyzed by using our analytical procedure and discusses about non-radiative recombination, optical and resistance losses in those tandem solar cells. The perovskite/Si 2-junction tandem solar cells is shown to have efficiency potential of 37.4% as a result of non-radiative recombination loss of 2.3%, optical loss of 2.7% and resistance loss of 3.1%. Although the perovskite/Si 3-junction tandem solar cells are thought to be very attractive because of higher efficiency with an efficiency of more than 42%, decreasing non-radiative recombination loss in wide bandgap perovskite solar cell materials is pointed out to be necessary.

Absorption enhancement in thin film a-Si solar cells with double-sided SiO_2 particle layers

Light absorption enhancement is very important for improving the power conversion efficiency of a thin film a-Si solar cell. In this paper, a thin-film a-Si solar cell model with double-sided SiO2 particle layers is designed, and then the underlying mechanism of absorption enhancement is investigated by finite difference time domain（FDTD） simulation;finally the feasible experimental scheme for preparing the SiO2 particle layer is discussed. It is found that the top and bottom SiO2 particle layers play an important role in anti-reflection and light trapping, respectively. The light absorption of the cell with double-sided SiO2 layers greatly increases in a wavelength range of 300 nm-800 nm, and the ultimate efficiency increases more than 22% compared with that of the flat device. The cell model with double-sided SiO2 particle layers reported here can be used in varieties of thin film solar cells to further improve their performances.

Research on the optimum hydrogenated silicon thin films for application in solar cells

Hydrogenated silicon （Si：H） thin films for application in solar ceils were deposited by using very high frequency plasma enhanced chemical vapour deposition （VHF PECVD） at a substrate temperature of about 170 ℃, The electrical, structural, and optical properties of the films were investigated. The deposited films were then applied as i-layers for p-i-n single junction solar cells. The current-voltage （I - V） characteristics of the cells were measured before and after the light soaking. The results suggest that the films deposited near the transition region have an optimum properties for application in solar cells. The cell with an i-layer prepared near the transition region shows the best stable performance.

基于硅纳米线的PEDOT:PSS/Si杂化太阳电池结构优化及实验研究

硅纳米线(silicon nanowires,SiNWs)越长,光学性能越好,但这会使太阳电池的电学性能损失越来越大。采用模拟和实验的方法,对PEDOT:PSS/Si杂化太阳电池的SiNWs进行优化,重点研究了SiNWs长度造成的表面复合速率和串联电阻对太阳电池性能的影响。结果表明,随着SiNWs长度的增加,表面复合主要影响开路电压,对太阳电池的性能影响较大;串联电阻主要影响填充因子,对太阳电池的性能影响较小。实验证明,当SiNWs长度为246nm左右时,PEDOT:PSS/Si杂化太阳电池的转换效率最高,为12.88%。研究结果可为含SiNWs的硅基太阳电池的设计提供指导。

Approaches for High-Efficiency III-V/Si Tandem Solar Cells

The Si tandem solar cells are very attractive for realizing high efficiency and low cost. This paper overviews current status of III-V/Si tandem solar cells including our results. The analytical results for efficiency potential of Si tandem solar cells and loss analysis of Si bottom cells as well as bandgap energy optimization of sub-cells are presented. The 2-junction and 3-junction Si tandem solar cells have potential efficiencies of 36% and 42%, respectively. ERE (external radiative efficiency) analysis for Si solar cells is analyzed in order to clarify properties of Si bottom solar cells. Properties of single-crystalline Si heterojunction solar cell fabricated in this study were analyzed. The current status of efficiencies of our Si bottom cell, upper III-V 2-junction solar cell and III-V/Si 3-junction tandem solar cell was shown to be 5.2% and 28.6% and 33.8%. Achievement of Jsc of 12 mA/cm2 for Si bottom cell is necessary to realize high-efficiency 3-junction Si tandem solar cells with an efficiency of more than 37%. In addition, this paper presents ERE analysis of III-V 2-junction upper solar cells for improving III-V/Si 3-junction tandem solar cells. Several ways to improve efficiency of III-V/Si 3-junction tandem solar cells by reducing non-radiative recombination, optical and resistance losses are shown.

Improving the performance of crystalline Si solar cell by high-pressure hydrogenation

We report an approach of high-pressure hydrogenation to improve the performance of crystalline Si(c-Si) solar cells.As-received p-type c-Si wafer-based PN junctions were subjected to high-pressure(2.5 MPa) hydrogen atmosphere at 200 ℃,followed by evaporating antireflection layers,passivation layers,and front and rear electrodes.The efficiency of the so prepared c-Si solar cell was found to increase evidently after high-pressure hydrogenation,with a maximal enhancement of 10%.The incorporation of hydrogen by Si solar cells was identified,and hydrogen passivation of dangling bonds in Si was confirmed.Compared to the regular approach of hydrogen plasma passivation,the approach of high-pressure hydrogenation reported here needs no post-hydrogenation treatment,and can be more convenient and efficient to use in improving the performances of the c-Si and other solar cells.

NT4(Si)-p53(N15)-antennapedia induces cell death in a human hepatocellular carcinoma cell line

AIM:To construct the recombinant lentivirus expression plasmid,pLenti6/V5-NT4 p53(N15)-antennapedia(Ant),and study its effect on HepG2 cells.METHODS:Plasmid pLenti6/V5-NT4 p53(N15)-Ant was constructed incorporating the following functional regions,including signal peptide sequence and pro-region of neurotrophin 4,N-terminal residues 12-26 of p53 and 17 amino acid drosophila carrier protein,Ant.Hepatocellular carcinoma(HepG2)cells were used for transfection.3-[4,5-dimethyl-thiazol-2yl]-2,5 diphenyl tetrazolium bromide(MTT)assay,lactate dehydrogenase(LDH)release assay,transmission electron microscopy(TEM)and flow cytometric analysis(FCM)were employed to investigate the effects of LV-NT4(Si)-p53(N15)-Ant in vitro on HepG2 cells.In vivo experiment was also performed to investigate the inhibitory effect of LV-NT4(Si)-p53(N15)-Ant on tumor growth in nude mice.RESULTS:LV-NT4(Si)-p53(N15)-Ant significantly suppressed the growth of HepG2 cells.MTT assay showed that the growth of HepG2 cells was mucj more significantly inhibited by LV-NT4(Si)-p53(N15)-Ant than by LV-EGFP.The inhibition rate for HepG2 cell growth in the two groups was 46.9% and 94.5%,respectively,48 h after infection with LV-NT4(Si)-p53(N15)-Ant,and was 33.9% and 95.8%,respectively,72 h after infection with LV-NT4(Si)-p53(N15)-Ant(P < 0.01).Light microscopy and TEM showed morphological changes in HepG2 cells infected with LV-NT4(Si)-p53(N15)-Ant,but no signif icant changes in HepG2 cells infected with LV-EGFP.Changes were observed in ultra-structure of HepG2 cells infected with LV-NT4(Si)-p53(N15)-Ant,with degraded membranes,resulting in necrosis.LDH release from HepG2 cells was analyzed at 24,48,72 and 96 h after infection with LV-NT4(Si)-p53(N15)-Ant and LV-EGFP,which showed that LDH release was signif icantly higher in LV-NT4(Si)-p53(N15)-Ant treatment group(682 IU/L)than in control group(45 IU/L,P < 0.01).The longer the time was after infection,the bigger the difference was in LDH release.FCM analysis showed that LV-NT4(Si)-p53(N15)-Ant could induce two different kinds of cell death:necrosis and apoptosis,with apoptosis being the minor type and necrosis being the main type,suggesting that LV-NT4(Si)-p53(N15)-Ant exerts its anticancer effect on HepG2 cells by inducing necrosis.The in vivo study showed that LV-NT4(Si)-p53(N15)-Ant significantly inhibited tumor growth with an inhibition rate of 66.14% in terms of tumor size and weight.

Simulation and experimental study of a novel bifacial structure of silicon heterojunction solar cell for high efficiency and low cost

A novel structure of Ag gridlSiNx/n＋-c-Si/n-c-Si/i-a-Si：H/p＋-a-Si：HlTCO/Ag grid was designed to increase the ef- ficiency of bifacial amorphous/crystalline silicon-based solar cells and reduce the rear material consumption and production cost. The simulation results show that the new structure obtains higher efficiency compared with the typical bifa- cial amorphous/crystalline silicon-based solar cell because of an increase in the short-circuit current （Jsc）, while retaining the advantages of a high open-circuit voltage, low temperature coefficient, and good weak-light performance. Moreover, real cells composed of the novel structure with dimensions of 75 mm×75 mm were fabricated by a special fabrication recipe based on industrial processes. Without parameter optimization, the cell efficiency reached 21.1% with the Jsc of 41.7 mA/cm^2. In addition, the novel structure attained 28.55% potential conversion efficiency under an illumination of AM 1.5 G, 100 mW/cm^2. We conclude that the configuration of the Ag grid/SiNx/n＋-c-Si/n-c-Si/i-a-Si：H/p＋-a-Si：H/TCO/Ag grid is a promising structure for high efficiency and low cost.

Spherical silicon solar cell with reflector cup fabricated by decompression dropping method

A spherical Si solar cell with a reflector cup was successfully fabricated by a dropping method at decompression state. In the dropping method, melted Si droplets were instilled at decompression state (0.5×105 Pa) to reduce crystal growth rate, dominating crystal quality such as dislocation density in crystal grains. Spherical Si solar cells were fabricated using the spherical Si crystals with a diameter of 1 mm and then mounted on a reflector cup. The current-voltage measurement of the solar cell shows an energy conversion efficiency of 11.1% (short-circuit current density (Jsc): 24.7 mA·cm-2, open-circuit voltage: 601 mV, fill factor: 74.6%). Minority carrier diffusion length determined by surface photovoltage method was 98 μm. This value can be enhanced by the improvement of crystal quality of spherical Si crystals. These results demonstrate that spherical Si crystals fabricated by the dropping method has a great potential for substrate material of high-efficiency and low-cost solar cells.

An analytical model to explore open-circuit voltage of a-Si:H/c-Si heterojunction solar cells

The effect of the parameters on the open-circuit voltage, V_(OC) of a-Si:H/c-Si heterojunction solar cells was explored by an analytical model. The analytical results show that V_(OC) increases linearly with the logarithm of illumination intensity under usual illumination. There are two critical values of the interface state density(D_(it)) for the open-circuit voltage(V_(OC)), D_(it)^(crit,1) and D_(it)crit,2(a few 1010 cm^(-2)·e V^(-1)). V_(OC) decreases remarkably when D_(it) is higher than D_(it)^(crit,1). To achieve high V_(OC), the interface states should reduce down to a few 1010 cm^(-2)·e V^(-1). Due to the difference between the effective density of states in the conduction and valence band edges of c-Si, the open-circuit voltage of a-Si:H/c-Si heterojunction cells fabricated on n-type c-Si wafers is about 22 mV higher than that fabricated on p-type c-Si wafers at the same case. V_(OC) decreases with decreasing the a-Si:H doping concentration at low doping level since the electric field over the c-Si depletion region is reduced at low doping level. Therefore, the a-Si:H layer should be doped higher than a critical value of 5×10^(18) cm^(-3) to achieve high V_(OC).

Methyl Termination and ATR-FTIR Evaluation of n-Si(111) Electrode towards Photoelectrochemical Cell Fabrication

We confirmed methyl termination on n-Si(111) surface by ATR-FTIR measurement, which was fabricated by a photo chloro-reaction and its methylation. The coverage of the methylation was about 63.7%, and the surface was not re-terminated by hydrogen. Photoelectrochemical properties of the n-Si(111) were measured as an electrode for a photoelectrochemical cell, and an onset potential obtaining photocurrent for the methyl terminated n-Si(111) electrode was observed as negative shift at 70 mV comparing with that of the hydrogen terminated n-Si(111) electrode. Therefore, the negative shift would be expected for improving open circuit voltage towards solar cell.

Simulation analysis of a high efficiency GaInP/Si multijunction solar cell

The solar power conversion efficiency of a gallium indium phosphide(GaInP)/silicon(Si)tandem solar cell has been investigated by means of a physical device simulator considering both mechanically stacked and monolithic structures.In particular,to interconnect the bottom and top sub-cells of the monolithic tandem,a gallium arsenide(GaAs)-based tunnel-junction,i.e.GaAs(n+)/GaAs(p+),which assures a low electrical resistance and an optically low-loss connection,has been considered.The J–V characteristics of the single junction cells,monolithic tandem,and mechanically stacked structure have been calculated extracting the main photovoltaic parameters.An analysis of the tunnel-junction behaviour has been also developed.The mechanically stacked cell achieves an efficiency of 24.27%whereas the monolithic tandem reaches an efficiency of 31.11%under AM1.5 spectral conditions.External quantum efficiency simulations have evaluated the useful wavelength range.The results and discussion could be helpful in designing high efficiency monolithic multijunction GaInP/Si solar cells involving a thin GaAs(n+)/GaAs(p+)tunnel junction.

Status of Selective Emitters for p-Type c-Si Solar Cells

Crystalline silicon (c-Si) solar cells have the lion share in world PV market. Solar cells made from crystalline silicon have lower conversion efficiency, hence optimization of each process steps are very important. Achieving low-cost photovoltaic energy in the coming years will depend on the development of third-generation solar cells. Given the trend towards these Si materials, the most promising selective emitter methods are identified to date. Current industrial monocrystalline Cz Si solar cells based on screen-printing technology for contact formation and homogeneous emitter have an efficiency potential of around 18.4%. Limitations at the rear side by the fully covering Al-BSF can be changed by selective emitter designs allowing a decoupling and separate optimization of the metallised and non-metallised areas. Several selective emitter concepts that are already in industrial mass production or close to it are presented, and their specialties and status concerning cell performance are demonstrated. Key issues that are considered here are the cost-effectiveness, added complexity, additional benefits, reliability and efficiency potential of each selective emitter tech- niques.