Determination of the Base Optimum Thickness of Back Illuminated (n+/p/p+) Bifacial Silicon Solar Cell, by Help of Diffusion Coefficient at Resonance Frequency

The bifacial silicon solar cell subjected to a magnetic field, is illuminated by the back side by a monochromatic light in frequency modulation, with high absorption, At minority carriers diffusion coefficient resonance frequency, a graphical study of the expressions of recombination velocity on the rear side is carried out. The optimum thickness of the base of the bifacial solar cell is deduced for each resonance frequency.

AC Back Surface Recombination Velocity as Applied to Optimize the Base Thickness under Temperature of an (n+-p-p+) Bifacial Silicon Solar Cell, Back Illuminated by a Light with Long Wavelength

The bifacial silicon solar cell, placed at temperature (T) and illuminated from the back side by monochromatic light in frequency modulation (ω), is studied from the frequency dynamic diffusion equation, relative to the density of excess minority carriers in the base. The expressions of the dynamic recombination velocities of the minority carriers on the rear side of the base Sb1(D(ω, T);H) and Sb2(α, D(ω, T);H), are analyzed as a function of the dynamic diffusion coefficient (D(ω, T)), the absorption coefficient (α(λ)) and the thickness of the base (H). Thus their graphic representation makes it possible to go up, to the base optimum thickness (Hopt(ω, T)), for different temperature values and frequency ranges of modulation of monochromatic light, of strong penetration. The base optimum thickness (Hopt(ω, T)) decreases with temperature, regardless of the frequency range and allows the realization of the solar cell with few material (Si).

Corneal endothelial cell density and morphology and central corneal thickness in Guangxi Maonan and Han adolescent students of China

AIM: To investigate the corneal endothelial cell density and morphology and central corneal thickness in the Guangxi Maonan and Han adolescent students of China.METHODS: Noncontact specular microscope(Topcon SP3000 P, Tokyo, Japan) was performed in 133 adolescent students of Maonan ethnic group(M:F 54:79)and 105 adolescent students of Han ethnic group(M:F 50:55),5 to 20 y of age, who were randomly selected from 3schools in Huanjiang Maonan Autonomous County of Guangxi Zhuang Autonomous Region of China.Parameters studied included endothelial cell density,mean cell area, coefficient of variation in cell size,percentage hexagonality and central corneal thickness. RESULTS: Endothelial cell density, mean cell area,coefficient of variation in cell size, percentage hexagonality and central corneal thickness in the study population were(2969.50 ±253.93) cells/mm2,(339.23 ±29.44) μm2,(29.96 ±4.07) %,(64.58 ±9.41) % and(523.71 ±32.82) μm in Maonan and(2998.26 ±262.65) cells/mm2,(336.11±30.07) μm2,(29.89±5.03) %,(64.91±11.64) % and(524.39 ±33.15) μm in Han, respectively. No significant differences were observed in endothelial cell density,mean cell area, coefficient of variation in cell size,percentage hexagonality and central corneal thickness between Maonan and Han(P =0.615, 0.659, 0.528, 0.551,0.999). In Maonan and Han, we found age was negatively correlated with endothelial cell density and percentagehexagonality and positively correlated with mean cell area and coefficient of variation in cell size. Negative correlation was also found between central corneal thickness and age in Han, whereas no correlation was found in Maonan. CONCLUSION: There were no differences between Maonan and Han in corneal endothelial cell density and morphology and central corneal thickness. In these two ethnic groups, there were statistically significant decrease in endothelial cell density and percentage hexagonality with increasing age and statistically significant increase in cell area and coefficient of variation in cell size with increasing age. Central corneal thinned with increasing age in Han, whereas difference did not attain statistical significance in Maonan.

Base Thickness Optimization of a (n+-p-p+) Silicon Solar Cell in Static Mode under Irradiation of Charged Particles

In this work, we propose a method to determinate the optimum thickness of a monofacial silicon solar cell under irradiation. The expressions of back surface recombination velocity depending the damage coefficient (kl) and irradiation energy (øp) are established. From their plots, base optimum thickness is deduced from the intercept points of the curves. The short-circuit currents Jsc0 and Jsc1 corresponding to the recombination velocity Sb0 and Sb1 are determinated and a correlation between the irradiation energy, the damage coefficient and optimum thickness of the base is established.

Manifestations of type 2 diabetes in corneal endothelial cell density,corneal thickness and intraocular pressure

We sought to evaluate central corneal thickness（CCT）,corneal endothelial cell density（ECD）and intraocular pressure（IOP）in patients with type 2 diabetes mellitus（DM）and to associate potential differences with diabetes duration and treatment modality in a prospective,randomized study.We measured ECD,CCT and IOP of125 patients with type 2 DM（mean age 57.1±11.5 years）and compared them with 90 age-matched controls.Measured parameters were analyzed for association with diabetes duration and glucose control modalities（insulin injection or oral medication）while controlling for age.In the diabetic group,the mean ECD（2511±252 cells/mm^2）,mean CCT（539.7±33.6μm）and mean IOP（18.3±2.5 mmHg）varied significantly from those the control group[ECD：2713±132 cells/mm^2（P〈0.0001）,CCT：525.0±45.3μm（P=0.003）and IOP：16.7±1.8 mmHg（P〈0.0001）].ECD was significantly reduced by about 32 cell/mm^2 for diabetics with duration of〉10 years when compared with those with duration of〈10 years（P〈0.05）.CCT was thicker and IOP was higher for diabetics with duration of〉10 years than those with duration of〈10 years（P〉0.05）.None of the measured parameters was significantly associated with diabetes duration and treatment modality（P〉0.05）.In conclusion,subjects with type 2DM exhibit significant changes in ECD,IOP and CCT,which,however,are not correlated with disease duration or if the patients receive on insulin injection or oral medications.

Correlating Photovoltaic Performance of Dye-Sensitized Solar Cell to the Film Thickness of Titania via Numerical Drift-Diffusion Simulations

TiO 2 电影的厚度是重要的认识到染料的光电的性能上的优化敏化太阳能电池(DSSC ) 。此处，在 DSSC 的费用分离的过程被使用一个飘移散开模型模仿。这个模型在电解质与电子领受人允许产生相片的电子，以及背反应的多重套住的散开，到处于稳定、非稳定的状态被模仿。当前电压的特征上的数字结果允许力量变换效率被改变 TiO 2 电影的厚度最大化。充电收集效率被显示与电影厚度减少，而电子注射的流动得益于变厚的电影。光电流的产量被二个因素实际上影响。而且，再结合率常数被发现显著地影响优化电影厚度。更厚的 TiO 2 电影对背反应足够地在被压制的 DSSC 合适。相反，与显示出快电子拦截的氧化还原作用夫妇一起的 DSSC 要求更薄的电影经由再结合减轻费用损失。在开的电路，电子密度被发现与电影厚度减少，它产生不仅 photovoltage 的减小而且电子一生的增加。

n⁺-p-p⁺Silicon Solar Cell Base Optimum Thickness Determination under Magnetic Field

Base optimum thickness is determined for a front illuminated bifacial silicon solar cell n+-p-p+ under magnetic field. From the magneto transport equation relative to excess minority carriers in the base, with specific boundary conditions, the photocurrent is obtained. From this result the expressions of the carrier’s recombination velocity at the back surface are deducted. These new expressions of recombination velocity are plotted according to the depth of the base, to deduce the optimum thickness, which will allow the production, of a high short-circuit photocurrent. Calibration relationships of optimum thickness versus magnetic field were presented according to study ranges. It is found that, applied magnetic field imposes a weak thickness material for solar cell manufacturing leading to high short-circuit current.

Back Illuminated N/P/P⁺Bifacial Silicon Solar Cell under Modulated Short-Wavelength: Determination of Base Optimum Thickness

A bifacial silicon solar cell under monochromatic illumination in frequency modulation by the rear side is being studied for the optimization of base thickness. The density of photogenerated carriers in the base is obtained by resolution of the continuity equation, with the help of boundary conditions at the junction surface (n+/p) and the rear face (p/p+) of the base. For a short wavelength corresponding to a high absorption coefficient, the AC photocurrent density is calculated and represented according to the excess minority carrier’s recombination velocity at the junction, for different modulation frequency values. The expression of the AC recombination velocity of excess minority carriers at the rear surface of the base of the solar cell is then deduced, depending on both, the absorption coefficient of the silicon material and the thickness of the base. Compared to the intrinsic AC recombination velocity, the optimal thickness is extracted and modeled in a mathematical relationship, as a decreasing function of the modulated frequency of back illumination. Thus under these operating conditions, a maximum short-circuit photocurrent is obtained and a low-cost bifacial solar cell can be achieved by reducing material (Si) to elaborate the base thickness.

A.C. Recombination Velocity as Applied to Determine n⁺/p/p⁺Silicon Solar Cell Base Optimum Thickness

This work deals with determining the optimum thickness of the base of an n+/p/p+ silicon solar cell under monochromatic illumination in frequency modulation. The continuity equation for the density of minority carriers generated in the base, by a monochromatic wavelength illumination (λ), with boundary conditions that impose recombination velocities (Sf) and (Sb) respectively at the junction and back surface, is resolved. The ac photocurrent is deduced and studied according to the recombination velocity at the junction, to extract the mathematical expressions of recombination velocity (Sb). By the graphic technique of comparing the two expressions obtained, depending on the thickness (H) of the base, for each frequency, the optimum thickness (Hopt) is obtained. It is then modeled according to the frequency, at the long wavelengths of the incident light. Thus, Hopt decreases due to the low relaxation time of minority carriers, when the frequency of modulation of incident light increases.

Advantages of InGaN/GaN multiple quantum well solar cells with stepped-thickness quantum wells

InGaN/GaN multiple quantum well （MQW） solar cells with stepped-thickness quantum wells （SQW） are designed and grown by metal-organic chemical vapor deposition. The stepped-thickness quantum wells structure, in which the well thickness becomes smaller and smaller along the growth direction, reveals better crystalline quality and better spectral overlap with the solar spectrum. Consequently, the short-circuit current density （Jsc） and conversion efficiency of the solar cell are enhanced by 27.12% and 56.41% compared with the conventional structure under illumination of AM1.5G （100 mW/cm2）. In addition, approaches to further promote the performance of InGaN/GaN multiple quantum well solar cells are discussed and presented.

Back Surface Recombination Velocity Dependent of Absorption Coefficient as Applied to Determine Base Optimum Thickness of an n+/p/p+ Silicon Solar Cell

The monochromatic absorption coefficient of silicon, inducing the light penetration depth into the base of the solar cell, is used to determine the optimum thickness necessary for the production of a large photocurrent. The absorption-generation-diffusion and recombination (bulk and surface) phenomena are taken into account in the excess minority carrier continuity equation. The solution of this equation gives the photocurrent according to absorption and electronic parameters. Then from the obtained short circuit photocurrent expression, excess minority carrier back surface recombination velocity is determined, function of the monochromatic absorption coefficient at a given wavelength. This latter plotted versus base thickness yields the optimum thickness of an n+-p-p+ solar cell, for each wavelength, which is in the range close to the energy band gap of the silicon material. This study provides a tool for improvement solar cell manufacture processes, through the mathematical relationship obtained from the thickness limit according to the absorption coefficient that allows base width optimization.

Visual acuity and endothelial cell density with respect to the graft thickness in Descemet's stripping automated endothelial keratoplasty: one year results

AIM: To evaluate the visual acuity and endothelial cell density according to the thickness in Descemet’s stripping automated endothelial keratoplasty(DSAEK)one year after surgery.METHODS: DSAEK patients’ data were reviewed. Thirty seven eyes of 37 patients who underwent DSAEK for pseudophakic bullous keratopathy(PBK) were included in this study. Graft thickness was measured with optical coherence tomography(OCT) 12 mo after DSAEK. Eyes were divided into 3 groups based on the graft thickness:thick(】200 μm), medium-thick(150-200 μm) and thin(【150 μm). Best corrected visual acuity(BCVA),endothelial cells density(ECD) and complications were assessed and comparisons were done between groups.RESULTS: Median thickness of postoperative grafts was 188(range 73-317 μm). There was no significant difference in age, sex, preoperative BCVA, or follow-up period between DSAEK groups. At postoperative 12 mo,mean BCVA was 0.28±0.10 in thick graft group, 0.52±0.08 in medium-thick graft group, and 0.72 ±0.06 in thin graft group. Thin grafts showed better postoperative BCVA as compared with the medium-thick and thick grafts(P =0.001). Thick graft group had 1637.44 ±88.19-mm2,medium thick graft had 1764.50±34.28-mm2 and thin graft group had 1845.30 ±65.62-mm2. Thin graft group had better ECD at 12 mo after surgery(P =0.001).CONCLUSION: Thin grafts after DSAEK ensure better visual rehabilitation. Eyes with thin grafts had significantly lesser loss of ECD compared to eyes withmedium-thick and thick grafts one year after surgery.

Analysis of the interdigitated back contact solar cells:The n-type substrate lifetime and wafer thickness

The n-type silicon integrated-back contact（IBC） solar cell has attracted much attention due to its high efficiency,whereas its performance is very sensitive to the wafer of low quality or the contamination during high temperature fabrication processing, which leads to low bulk lifetime τbulk. In order to clarify the influence of bulk lifetime on cell characteristics, two-dimensional（2D） TCAD simulation, combined with our experimental data, is used to simulate the cell performances, with the wafer thickness scaled down under various τbulk conditions. The modeling results show that for the IBC solar cell with high τbulk,（such as 1 ms-2 ms）, its open-circuit voltage V oc almost remains unchanged, and the short-circuit current density J sc monotonically decreases as the wafer thickness scales down. In comparison, for the solar cell with low τbulk（for instance, 〈 500 μs） wafer or the wafer contaminated during device processing, the V oc increases monotonically but the J sc first increases to a maximum value and then drops off as the wafer＇s thickness decreases. A model combing the light absorption and the minority carrier diffusion is used to explain this phenomenon. The research results show that for the wafer with thinner thickness and high bulk lifetime, the good light trapping technology must be developed to offset the decrease in J sc.

Retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness in children with obesity

AIM：To evaluate retinal nerve fiber layer（RNFL）thickness analysis of peripapillary optic nerve head（PONH） and macula as well as ganglion cell-inner plexiform layer（GCIPL） thickness in obese children.· METHODS：Eighty-five children with obesity and 30 controls were included in the study.The thicknesses of the PONH and macula of each subject＇s right eye were measured by high-resolution spectral-domain optic coherence tomography（OCT）.· RESULTS：The RNFL thicknesses of central macular and PONH were similar between the groups（all P 〉0.05）.The GCIPL thickness was also similar between the groups.However,the RNFL thickness of temporal outer macula were 261.7±13.7 and 268.9±14.3 μm for the obesity and the control group,respectively（P =0.034）.· CONCLUSION：Obesity may cause a reduction in temporal outer macular RNFL thickness.

Electrical Parameters Determination from Base Thickness Optimization in a Silicon Solar Cell under Influence of the Irradiation Energy Flow of Charged Particles

In this work, we study the characteristics I-V and P-V of a silicon solar cell as well as its fill factor, its electrical power from the optimum thickness obtained in the base under variation of the irradiation energy flow of charged particles. The recombination velocity at the junction corresponding to the maximum power point was also deduced.

Diffusion Coefficient at Resonance Frequency as Applied to n+/p/p+ Silicon Solar Cell Optimum Base Thickness Determination

The modelling and determination of the geometric parameters of a solar cell are important data, which influence the evaluation of its performance under specific operating conditions, as well as its industrial development for a low cost. In this work, an n+/p/p+ crystalline silicon solar cell is studied under monochromatic illumination in modulation and placed in a constant magnetic field. The minority carriers’ diffusion coefficient (D(ω, B), in the (p) base leads to maximum values (Dmax) at resonance frequencies (ωr). These values are used in expressions of AC minority carriers recombination velocity (Sb(Dmax, H)) in the rear of the base, to extract the optimum thickness while solar cell is subjected to these specific conditions. Optimum thickness modelling relationships, depending respectively on Dmax, ωr and B, are then established, and will be data for industrial development of low-cost solar cells for specific use.

Surface Recombination Concept as Applied to Determinate Silicon Solar Cell Base Optimum Thickness with Doping Level Effect

New expressions of back surface recombination of excess minority carriers in the base of silicon solar are expressed dependent on both, the thickness and the diffusion coefficient which is in relationship with the doping rate. The optimum thickness thus obtained from the base of the solar cell allows the saving of the amount of material needed in its manufacture without reducing its efficiency.

Influence of Both Magnetic Field and Temperature on Silicon Solar Cell Base Optimum Thickness Determination

The minority carrier’s recombination velocity at the junction and at the back surface is used for the modeling and determination of the optimum thickness of the base of a silicon solar cell in the static regime, under magnetic field and temperature influence. This study takes into account the Umklapp process and the Lorentz effect on the minority carriers photogenerated in the base.

Shunt Resistance Determination in a Silicon Solar Cell: Effect of Flow Irradiation Energy and Base Thickness

The concept of the recombination of the minority carrier’s recombination velocity at the junction and in the rear, is used for determination, optimum thickness and then shunt resistance in the base of the silicon solar cell, maintained in steady state and under energy from the irradiation flow of charged particles. Resistance shunt is obtained and modeled through a relationship expressed according to the flow and energy of irradiation imposed on the solar cell.

雷珠单抗两种给药策略对糖尿病黄斑水肿视觉功能、中心凹视网膜厚度、角膜内皮细胞密度的影响

目的探讨雷珠单抗不同给药策略对糖尿病黄斑水肿(DME)视觉功能、中心凹视网膜厚度(FT)、角膜内皮细胞密度的影响。方法选取2020年6月至2022年6月郑州市第二人民医院眼科收治的60例DME患者作为研究对象,采用随机数表法分为常规组(30例39眼)和强化组(30例42眼),所有患者均予以玻璃体内注射雷珠单抗治疗,常规组患者予以3+按需治疗(PRN)给药方案,强化组予以5+PRN给药方案,两组患者均随访12个月观察疗效。比较两组患者PRN治疗期间患眼注射次数、补救性光凝次数,以及治疗3个月、6个月、9个月、12个月后的最佳矫正视力(BCVA)较基线提高字母数、黄斑中心凹厚度(FT)和治疗3个月、6个月、12个月后的角膜内皮细胞密度、六角形细胞比例、角膜神经变化,同时比较两组患者治疗期间的不良反应发生情况。结果强化组患者PRN治疗期间患眼注射次数、补救性光凝次数分别为(2.40±0.80)次、(1.12±0.30)次,明显少于常规组的(4.10±1.00)次、(1.97±0.64)次,差异均有统计学意义(P<0.05);强化组患者治疗6个月、9个月、12个月后患眼BCVA较基线提高字母数分别为(5.06±0.82)个、(7.83±1.21)个、(10.20±3.14)个,明显高于常规组的(4.30±0.77)个、(5.64±1.30)个、(8.96±2.55)个,差异均有统计学意义(P<0.05);强化组患者治疗12个月后患眼BCVA提高>10个字母患眼占66.67%,明显多于常规组的43.59%,差异均有统计学意义(P<0.05);强化组治疗9个月、12个月后患眼FT分别为(276.25±83.40)μm、(242.34±77.59)μm,明显低于常规组的(325.86±56.04)μm、(296.27±53.00)μm,差异均有统计学意义(P<0.05);两组患者治疗前后患眼角膜内皮细胞密度、六角形细胞比例、神经纤维长度、神经纤维密度比较差异均无统计学意义(P>0.05);两组患者治疗期间均未观察到不良反应发生。结论雷珠单抗3+PRN、5+PRN给药方案可安全治疗DME,且对角膜内皮细胞密度无明显影响,而在视觉功能、中心凹视网膜厚度、给药次数、药物经济性方面,5+PRN给药方案作用效果更优。