Effect of 10 MeV electron irradiation on dye-sensitized solar cells

The effect of 10?MeV electrons’ irradiation on dye-sensitized solar cells (DSSCs) has been studied in this paper. J–V characteristics measurements were carried out in order to investigate the degradation of the cells in electron radiation environments. The short-circuit current (J_sc) and maximum power density (P_max) of cells decrease significantly after the electron irradiation. When the irradiation dose increases to 10?kGy, the initial maximum power decreases nearly by 50%. The influences of the electron irradiation on FTO, dye sensitizer and anode were studied to investigate the degradation mechanism of DSSC, respectively. The ultraviolet–visible spectra of FTO show that the absorption peaks of dye decrease, resulting in a decline of the FTO transmittance. According to the X-ray diffraction measurement results, it was found that the particle size of nano-crystalline TiO₂ had changed after the electron irradiation. With the help of SEM, the conglomeration of TiO₂ nano-particles appears after the electron irradiation.     

位移损伤剂量法评估空间GaAs/Ge太阳电池辐照损伤过程

本文针对GaAs/Ge太阳电池,利用位移损伤剂量法研究了其在轨服役条件下的性能退化行为.首先在地面模拟辐照环境中,试验获得了在不同能量的电子和质子辐照下的电池性能随辐照注量的退化行为.基于上述实验结果以及计算获得的带电粒子在电池中的非电离能量损失(NIEL)获得了不同能量电子辐照位移损伤的等效指数n为1.7,电子损伤剂量转化为质子损伤剂量等效系数为5.2,并进一步建立了电池性能随位移损伤剂量的退化方程.利用该方法对国产GaAs/Ge太阳电池在500,22000和36000 km轨道带电粒子辐 关键词： GaAs/Ge太阳电池 辐照损伤 带电粒子 位移损伤剂量     

100 keV质子辐照对空间GaAs/Ge太阳电池光电效应的影响

利用空间环境模拟设备,用固定能量为100keV、注量为1×10⁹—3×10¹²cm^-2的质子,对空间实用GaAs/Ge太阳电池进行了辐照试验.利用伏安(I-V)特性、光谱响应和光致发光(PL)光谱测试,研究分析了电池的光电效应.试验表明,电池的各种电性能参数如短路电流(I_sc)、开路电压(V_oc)、最大输出功率(P_{m< 关键词： GaAs/Ge太阳电池 质子辐照 光电效应}     

Efficiency characteristics of a silicon oxide passivation layer on p-type crystalline silicon solar cell at low illumination

Silicon dioxide (SiO₂) is widely used to improve the surface passivation properties of silicon solar cells. To minimize solar cell potential-induced degradation when the PV module is installed outdoors, a silicon oxide film is widely used as an insulator. However, experiments have confirmed that solar cells with a silicon oxide (SiO₂) film have a lower efficiency than solar cells without a silicon oxide (SiO₂) film at low illumination (<0.4 sun). Actually, the efficiency in the low illumination condition affects the average power output per day because the PV module mostly operates when the solar irradiation dose is less than 1 sun. To maximize the performance of the PV module, the output at a low light intensity level should also be considered. Shunt resistance (R_shunt) is known to cause a decrease in solar cell efficiency under low illumination conditions. PC1D simulation was used to analyze parameters, such as the series resistance, parallel resistance, and surface recombination, that affect the characteristics of the solar cell at low light intensity. In this study, we confirmed how the SiO₂ layer affected the low illumination properties of solar cells, even though these cells were more efficient at 1 sun. Silicon solar cells with a SiN_x/SiO₂ bilayer or a SiN_x single film were fabricated, and their characteristics were evaluated. Passivation characteristics were measured using the quasi-steady-state photoconductance (QSSPC) technique to evaluate the minority carrier lifetime and the implied open-circuit voltage (V_OC), and capacitance-voltage measurements were used to analyze the fixed charges. The values of the shunt resistance and series resistance in solar cells with different passivation layers were compared, and the cause of the decrease in the efficiency under low illumination was also analyzed via fill factor calculation.     

Effect of bias condition on heavy ion radiation in bipolar junction transistor

The characteristic degradations in silicon NPN bipolar junction transistor (BJT) of 3DG142 type are examined under the irradiation with 40-MeV chlorine (Cl) ions under forward, grounded, and reverse bias conditions, respectively. Different electrical parameters are in-situ measured during the exposure under each bias condition. From the experimental data, larger variation of base current (I_B) is observed after irradiation at a given value of base-emitter voltage (V_BE), while the collector current is slightly affected by irradiation at a given V_BE. The gain degradation is affected mostly by the behaviour of the base current. From the experimental data, the variation of current gain in the case of forward bias is much smaller than that in the other conditions. Moreover, for 3DG142 BJT, the current gain degradation in the case of reverse bias is more severe than that in the grounded case at low fluence, while at high fluence, the gain degradation in the reverse bias case becomes smaller than that in the grounded case.     

Effectiveness of full spectrum light soaking on solar cell degradation analysis

This study examined the effect of UV-spectrum light soaking on solar cell degradation tests. An indoor light soaking test was evaluated over three different spectral ranges: “UV only”, “UV blocked” and “Full spectrum”. a-Si:H and poly-crystalline silicon solar cell technologies were studied by light soaking tests with the same optical filter configurations.The I–V measurement results demonstrated that “UV only” irradiated solar cells exhibited the smallest output power degradation, which was only half of a percent variation compared with the full spectrum light soaking case. Using a filter that excluded the effect of the UV spectral range on light soaking, the “UV blocked” case also exhibited a significant output power degradation of the solar cells. A comparative analysis of the solar cell response, based on the I–V characteristics and the diode ideality factor under these different light soaking spectra, demonstrated the importance of the full spectrum light soaking test in the evaluation of the long-term performance of solar cells.     

Spatial distribution of defects produced by boron ion implantation of silicon

A simple technique for the study of the spatial distribution of the damage produced by ion implantation of silicon has been developed. The damage depth distribution for 40 keV boron ions in silicon has been studied at irradiation doses from 7 × 10¹¹ to 3.9 × 10¹⁴ ions/cm² and the relative defect peak depth R _d/R _p = 0.85 determined. An increase of layer conductivity as the surface part of the implanted layer is removed has been revealed. This effect is caused by the presence of radiation defects in the surface region of the layer. The “electrical” cluster diameter is about 28 A and the overlapping cluster dose is close to 1 × 10¹³ ions/cm².     

n型掺杂层结构对n-i-p型微晶硅电池性能和光致衰退特性的影响

采用射频化学气相沉积法,制备了一系列具有不同晶化率n型掺杂层的n-i-p结构微晶硅薄膜太阳电池.发现本征层的结构很大程度上依赖于n型掺杂层的结构,特别是n/i界面处的孵化层厚度以及本征层的晶化率.该系列太阳电池在100 mW/cm²的白光下照射400 h,实验结果证实了本征层晶化率最大（X_c(i)=65%）的电池性能表现出最低的光致衰退率.拥有非晶/微晶过渡区n型掺杂层的电池（本征层晶化率X_c(i)=54%）分别 关键词： 微晶硅 n-i-p结构太阳电池 光致衰退 晶化率     

Evaluation and prediction of the degradation of space Si solar cells induced by a low-earth-orbit radiation environment

Space-graded silicon solar cells are evaluated by 1 MeV and 2 MeV electron-irradiation. The mean degradation of the maximum power (P_max) is presented and analyzed. The degradation at both electron energies has been correlated with the displacement damage dose (D_d). A good linearity between the electron D_d and the mean P_max degradation is obtained. The concept of D_d has also been used to predict the Si solar cell response in a low-earth-orbit (Altitude 799 km, Inclination 99^o) radiation environment, considering the shielded effect of a 120 μ m-thick silica coverglass on reducing the radiation. Compared with the on-orbit data from a Si solar array of a Chinese satellite (duration from April 2007 to July 2010), a good match can be found between the on-orbit data and the predicted results using D_d methodology, indicating the method is appropriate for evaluating the radiation damage of the solar cells, and also to provide a new technique for studying radiation effects on the optoelectronic detectors used in many high energy physics applications, where harsh radiation environments produce damage in optoelectronic device materials.     

Mössbauer study of proton radiation effects in FeCl24H2O

Abstract

The proton radiation effects in ferrous chloride are studied by means of the Mössbauer spectroscopy. The irradiation with protons of energy of 0.68 to 1.5 MeV has been found to cause dehydration and chemical decomposition of ferrous chloride. FeCl_{2 ·} 2H₂O, and Fe₃O₄ in superparamagnetic and ferromagnetic states, as well as Fe_1?x O were formed. The formation of a superparamagnetic phase of Fe₃O₄ within the “spike” regions was verified by low temperature measurements. The effects observed were interpreted in terms of the “thermal spike” model. The calculated temperatures and radii of “spikes” formed by iron, chloride and oxygen ions are in good agreement with observation for superparamagnetic Fe₃O₄.     

Swift heavy ions-induced degradation on the electrical characteristics of silicon NPN power transistors

ABSTRACT

The pre- and post-irradiation effects on the DC electrical characteristics of 100?MeV Phosphorous (P⁷⁺) and 80?MeV Nitrogen (N⁶⁺) ion-irradiated NPN transistors were studied in the dose range from 600?krad (Si) to 100?Mrad (Si). The different electrical characteristics, such as Gummel characteristics, excess base current (ΔI_B?=?I_B-Post?–?I_B-Pre), current gain (h_FE), damage constant (K) and output characteristics, were measured in situ after ion irradiation. The considerable increase in the base current (I_B) at lower V_BE and slight decrease in the collector current (I_C) at higher V_BE were observed after ion irradiation. The C–V measurements revealed that the doping concentration (N_d) was found decreased, while the built-in potential (V_bi) increased after irradiation. The ion-irradiated results are compared with ⁶⁰Co gamma-irradiated results in the same dose range. The SRIM simulation was performed to understand the range of ions and energy loss in the transistor structure. The SRIM simulation showed that 100?MeV P⁷⁺ and 80?MeV N⁶⁺ ions can easily pass through the active region of transistors by creating ionization and displacement damages in the device structure. The irradiation results showed that ions induce more degradation in the electrical characteristics when compared to ⁶⁰Co gamma radiation at the same dose range.     

Superstrate p-i-n a-Si:H solar cells on textured ZnO:Al front transparent conduction oxide

Superstrate p-i-n amorphous silicon thin-film (a-Si:H) solar cells are prepared on SnO₂:F and ZnO:Al transparent conducting oxides (TCOs) in order to see the effect of TCO/p-layers on a-Si:H solar cell operation. The solar cells prepared on textured ZnO:Al have higher open circuit voltage V_oc than cells prepared on SnO₂:F. The presence of a thin microcrystalline p-type silicon layer (μc-Si:H) between ZnO:Al and p a-SiC:H plays a major role by causing an improvement in the fill factor as well as in V_oc of a-Si:H solar cells prepared on ZnO:Al TCO. Without any treatment of the p-i interface, we could obtain a high V_oc of 994 mV while keeping the fill factor (72.7%) and short circuit current density J_sc at the same level as for the cells on SnO₂:F TCO. This high V_oc value can be attributed to modification in the current transport in this region due to creation of a potential barrier.     

硅片及其太阳电池的光衰规律研究

采用氙灯模拟太阳光源,将光强调至1000 W/m2,研究常规太阳能级单晶硅片、多晶硅片和物理提纯硅片的原片、去损减薄片、热氧化钝化片、双面镀氮化硅(SiN x:H)膜钝化片、碘酒钝化片以及太阳电池的光衰规律.利用WT-2000少子寿命测试仪以及太阳电池I-V特性测试仪分别对硅片的少子寿命和太阳电池的I-V特性参数随光照时间的变化进行了测试.结果表明:所有硅片以及太阳电池在光照的最初60 min内衰减很快随后衰减变慢,180 min之后光衰速率变得很小,几乎趋于零.     

Impact of average photon-energy coefficient of solar spectrum on the short circuit current of photovoltaic modules

The output energy of photovoltaic (PV) modules is influenced by the spectral irradiance distribution of the solar spectrum under outdoor conditions. To rate the precise output energy of PV modules, the correction of short circuit current (I_SC) based on actual environmental conditions is needed, because I_SC significantly depends on the shape of the spectral irradiance distribution. The average photon energy (APE) is a zero-dimensional index for spectral irradiance distribution, and APE value uniquely describes the shape of a solar spectrum. Thus, APE has an impact on I_SC of PV modules. In this contribution, the relationship between APE coefficient and I_SC of the multi-crystalline silicon, single-crystalline silicon, heterojunction intrinsic thin-layer, back contact, copper indium selenide and cadmium telluride PV modules has explored. It is revealed that APE value changes the I_SC of PV modules which appeared to have immense possibilities of I_SC correction using APE coefficient. This new approach can be very effective for precise rating the output energy of PV modules under actual outdoor conditions.     

Silicon heterojunction solar cell with amorphous silicon oxide buffer and microcrystalline silicon oxide contact layers

This Letter reports on the fabrication and characterization of silicon heterojunction solar cells with silicon oxide based buffer (intrinsic amorphous silicon oxide) and contact layers (doped microcrystalline silicon oxide) on flat p‐type wafers. The critical dependency of the cell performance on the front and rear buffer layer thickness reveals a trade‐off between the open circuit voltage V_oc and the fill factor FF. At the optimum, the highest efficiency of 18.5% (active area = 0.67 cm²) was achieved with V_oc = 664 mV, short circuit current J_sc = 35.7 mA/cm² and FF = 78.0%. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electrical properties and degradation behavior of hydrogenated amorphous Si alloys for solar cells

The electrical properties and the degradation behavior of hydrogenated amorphous silicon alloys (a-Si_1–x A _x : H, with A=C, Ge, B, P) in designs of pin, pip, nin, and MOS structures are investigated by measuring the dark and light I(V) characteristics and the spectral response as well as the space-charge-limited current (SCLC), the time of flight (TOF) of carriers and the field effect (FE). These investigations give an overview of our recent work combined with new results emphasizing the physics of the a-Si:H pin solar cells. We discuss the stabilizing influence on the degradation behavior achieved by profiling the i layers of the pin solar cells with P and B. Two kinds of pin solar cells, namely glass/SnO₂/p(C)in/metal and glass/metal/pin/ITO, are investigated and an explanation of their different spectral response behavior is given. SCLC measurements lead to the conclusion that trapping is also involved in the degradation mechanism, as is recombination. TOF experiments on a-Si_1–x Ge _x : H pin diodes indicate that the incorporation of Ge widens the tail-state distribution below the conduction band. FE measurements showed densities of gap states of about 5×l0¹⁶cm^–3eV^–1.     

Crystalline silicon solar cells with high resistivity emitter

The paper presents a part of research targeted at the modification of crystalline silicon solar cell production using screen-printing technology. The proposed process is based on diffusion from POCl₃ resulting in emitter with a sheet resistance on the level of 70 Ω/□ and then, shaped by high temperature passivation treatment. The study was focused on a shallow emitter of high resistivity and on its influence on output electrical parameters of a solar cell. Secondary ion mass spectrometry (SIMS) has been employed for appropriate distinguishing the total donor doped profile. The solar cell parameters were characterized by current-voltage characteristics and spectral response (SR) methods. Some aspects playing a role in suitable manufacturing process were discussed. The situation in a photovoltaic industry with emphasis on silicon supply and current prices of solar cells, modules and photovoltaic (PV) systems are described. The economic and quantitative estimation of the PV world market is shortly discussed.     

Potential‐induced optimization of ultra‐thin rear surface passivated CIGS solar cells

Ultra‐thin Cu(In,Ga)Se₂ (CIGS) solar cells with an Al₂O₃ rear surface passivation layer between the rear contact and absorber layer frequently show a “roll‐over” effect in the J–V curve, lowering the open circuit voltage (V_OC), short circuit current (J_SC) and fill factor (FF), similar to what is observed for Na‐deficient devices. Since Al₂O₃ is a well‐known barrier for Na, this behaviour can indeed be interpreted as due to lack of Na in the CIGS absorber layer. In this work, applying an electric field between the backside of the soda lime glass (SLG) substrate and the SLG/rear‐contact interface is investi‐gated as potential treatment for such Na‐deficient rear surface passivated CIGS solar cells. First, an electrical field of +50 V is applied at 85 °C, which increases the Na concentration in the CIGS absorber layer and the CdS buffer layer as measured by glow discharge optical emission spectroscopy (GDOES). Subsequently, the field polarity is reversed and part of the previously added Na is removed. This way, the J –V curve roll‐over related to Na deficiency disappears and the V_OC (+25 mV), J_SC(+2.3 mA/cm²) and FF (+13.5% absolute) of the rear surface passivated CIGS solar cells are optimized. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)