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现有1.0 eV/0.75 eV InGaAsP/InGaAs双结太阳电池的开路电压小于各子电池的开路电压之和,鲜有研究探索开路电压损耗的来源以及如何抑制.通过研究发现,InGaAs底电池背场/基区界面处的少数载流子输运的主要机制是热离子发射,而不是缺陷诱导复合.SIMS测试表明,采用InP或InAlAs背场均不能有效抑制Zn掺杂剂的扩散.此外,由于生长过程中持续的高温热处理,Ⅲ-Ⅴ族主元素在界面处发生了热扩散.为了抑制上述现象,提出了一种新型InP/InAlAs超晶格背场,并应用到InGaAs底电池中.制备得到的双结太阳电池在维持短路电流密度不变的情况下,开路电压提升到997.5 mV,与传统采用InP背场的双结太阳电池相比,开路电压损耗降低了30 mV.该研究成果对提升四结太阳电池的整体开路电压有重要意义.“,”Smaller Voc of 1. 0 eV/0. 75 eV InGaAsP/InGaAs double-junction solar cell(DJSC)than the Voc sum ofindividual subcells has been observed,and there is little information of the origin of such Voc loss and how to mini-mize it. In this paper,it is disclosed that the dominant mechanism of minority-carrier transport at back-surface-field(BSF)/base interface of the bottom subcell is thermionic emission,instead of defect-induced recombination, which is in contrast to previous reports. It also shows that both InP and InAlAs cannot prevent the zinc diffusion effectively. In addition,intermixing of major Ⅲ-Ⅴ element occurs as a result of increasing thermal treatment. To suppress the above negative effects,an initial novel InP/InAlAs superlattice(SL)BSF layer is then proposed and employed in bottom InGaAs subcell. The Voc of fabricated cells reach 997. 5 mV,and a reduction of 30 mV in Voc loss without lost of Jsc,compared with the results of conventional InP BSF configuration,is achieved. It would benefit the overall Voc for further four-junction solar cells.