【摘要】：由于四結(jié)太陽電池相比三結(jié)陽電池具有更高的光電轉(zhuǎn)換效率,將逐步取代目前普遍使用的三結(jié)太陽電池。目前多結(jié)太陽電池主要應(yīng)用于太空中航天器的供電系統(tǒng),而其間存在的高能粒子的持續(xù)轟擊將導(dǎo)致其性能逐步降低,因此太陽電池的耐輻照性能在很大程度上決定了航天器的壽命。目前三結(jié)太陽電池相關(guān)的輻照損傷研究已經(jīng)開展10年以上且還在持續(xù)被研究中,但是四結(jié)太陽電池的相關(guān)研究還屬于空白領(lǐng)域。多結(jié)太陽電池輻照效應(yīng)研究需要從實驗測試和理論分析兩方面進(jìn)行。測試方面涉及的方向很多,本工作主要關(guān)注電學(xué)性能的衰減,因此本文主要測量四結(jié)太陽電池的輻照前后的短路電流密度Jsc和開路電壓Voc的衰減。理論方面需要原子級別的高能粒子轟擊半導(dǎo)體的仿真軟件和器件級別的計算機輔助軟件。對于原子級別的仿真,本工作選用基于第一性原理的Casino軟件對高能粒子注入到多層薄膜中的能量吸收進(jìn)行計算;器件的性能仿真,采用加拿大Crosslight公司的Apsys軟件進(jìn)行分析。本工作分為實驗和理論分析兩部分。實驗方面,參與制備出了四結(jié)太陽電池并通過合理選擇輻照電子的能量和注量,測試了輻照前后的Jsc和Voc�？紤]到統(tǒng)計學(xué)因素,選擇了5組相近的測量結(jié)果計算其平均值,得到Jsc在輻照后從15.69mA/cm2衰減為13.55mA/cm2,Voc從3276.76mV衰減到2902.64mV。理論分析分為輻照前和輻照后兩部分。輻照前的理論分析使用Apsys軟件進(jìn)行器件仿真�？紤]到工藝中產(chǎn)生的缺陷問題,提出“多結(jié)太陽電池的單結(jié)分析法”,分析了少數(shù)載流子壽命和陷阱密度對各子結(jié)Jsc的影響趨勢,結(jié)果表明:第三結(jié)子電池的Jsc對缺陷最敏感,從而判斷其為四結(jié)太陽電池的電流限制結(jié)。少數(shù)載流子壽命分析是普遍采用的方法,陷阱密度的分析屬于首次采用,而陷阱密度更能體現(xiàn)晶格中的缺陷情況。在確定電流限制結(jié)后,通過調(diào)整其它三個子結(jié)的陷阱密度,得到了擬合實驗的結(jié)果,仿真得到的Jsc和Voc的誤差只有0.1%左右。輻照后的理論分析首先使用Casino軟件進(jìn)行高能電子輻照仿真,接著使用Apsys軟件進(jìn)行仿真分析。由于Casino軟件不能完整仿真四結(jié)太陽電池的薄膜結(jié)構(gòu),因此使用各子結(jié)電池吸收高能粒子能量的“能量損失遞減”方法,由此得到在1MeV電子輻照的情況下,各子結(jié)的吸收平均能量分別為27.3 keV,28.24keV,27.8keV和29.3keV。電子輻照產(chǎn)生的晶格缺陷在載流子的輸運過程中表現(xiàn)為陷阱。為了體現(xiàn)每個子結(jié)吸收的電子能量轉(zhuǎn)化為陷阱的能力,本文嘗試采用“吸收能量和陷阱密度表征的方法”,其相應(yīng)的Apsys軟件仿真分析得出,第3結(jié)子電池依然是輻照后的電流限制結(jié)。通過改變各個子結(jié)的吸收電子能量轉(zhuǎn)化陷阱能力的表征值,同樣得到了擬合實驗的結(jié)果,仿真得到的J-V曲線非常逼近輻照后的實驗測量J-V曲線。四結(jié)太陽電池分析工作還處于初期階段,后續(xù)可以開展許多方面的完善性工作,比如測量各層薄膜材料的電學(xué)性質(zhì)和各子結(jié)吸收材料的折射率譜以得到電池的精確仿真結(jié)果,以此為前提進(jìn)行電池的精確優(yōu)化工作。本文中提出的一系列理論結(jié)合實驗的分析方法不限于應(yīng)用于四結(jié)太陽電池,對于將來五結(jié)太陽電池甚至六結(jié)太陽電池的分析和優(yōu)化都是行之有效的方法。
[Abstract]:Because the four-junction solar cell has higher photoelectric conversion efficiency compared with the three-junction solar cell, the three-junction solar cell currently commonly used is gradually replaced. At present, the multi-junction solar cell is mainly applied to the power supply system of the spacecraft in space, and the continuous bombardment of the high-energy particles in the space can lead to a gradual reduction in the performance of the solar cell, so that the radiation resistance performance of the solar cell largely determines the life of the spacecraft. At present, the research on the radiation damage associated with the three-junction solar cell has been carried out more than 10 years and is still under study, but the related research of the four-junction solar cell also belongs to the blank field. The study of the radiation effect of multi-junction solar cells needs to be carried out from both experimental and theoretical analysis. In this paper, the short-circuit current density (Jsc) and the open-circuit voltage (Voc) before and after the irradiation of the four-junction solar cell are mainly measured. The theoretical aspect requires the atomic level of high-energy particles to bombard the semiconductor's simulation software and device-level computer-aided software. For the simulation of the atomic level, the energy absorption of high-energy particles into the multi-layer film is calculated by the Casino software based on the first principle, and the performance simulation of the device is carried out by using the Apsys software of Crosslight, Canada. This work is divided into two parts: experimental and theoretical analysis. In the experimental aspect, the four-junction solar cell was prepared and the energy and the injection quantity of the irradiated electrons were selected reasonably, and the Jsc and Voc before and after irradiation were tested. Taking into account the statistical factors, the average value of 5 groups of similar measurements was selected to obtain the average value of Jsc from 15. 69mA/ cm2 to 13.55mA/ cm2 after irradiation and from 3276.76mV to 2902. 64mV. The theoretical analysis is divided into two parts before and after irradiation. The theoretical analysis before irradiation uses the Apsys software for device simulation. In this paper, the influence of minority carrier lifetime and trap density on sub-junction Jsc is analyzed, and the effect of minority carrier lifetime and trap density on sub-junction Jsc is analyzed. The results show that the Jsc of the third junction cell is most sensitive to the defect, so as to judge the current limiting junction of the four-junction solar cell. The analysis of minority carrier lifetime is a widely used method. The analysis of the trap density belongs to the first use, and the trap density can reflect the defects in the lattice. After the current limit junction is determined, the trap density of the other three sub-junctions is adjusted, and the result of the fitting experiment is obtained, and the error of the obtained Jsc and Voc is only 0.1%. The theoretical analysis after irradiation firstly uses the Casino software for high-energy electronic irradiation simulation, and then uses the Apsys software to carry out the simulation analysis. Since the Casino software does not fully simulate the thin-film structure of the four-junction solar cell, the 鈥渆nergy loss decrements鈥，

本文編號：2414115