High efficiency infrared PbS quantum dot solar cells toward the bottom subcell of tandem solar cells
作者单位：RCASTThe University of Tokyo
会议名称：《第六届新型太阳能电池材料科学与技术学术研讨会》
会议日期：2019年
学科分类：081702[工学-化学工艺] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070205[理学-凝聚态物理] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0702[理学-物理学]
关 键 词：Lead(Ⅱ) sulfide Colloidal quantum dots ZnO Nanowires Infrared
摘 要：Development of ultra-high efficiency low cost tandem solar cell is required for efficient utilization of solar energy. For the purpose, PbS colloidal quantum dots(CQDs) have been gaining much attention as promising constituent materials for solution processed-infrared solar cells because PbS QDs can absorb photon energy in a wider range of the solar spectrum. Among various CQD-based solar cells, PbS QD/ZnO-based depleted heterojunction solar cells showed a power conversion efficiency(PCE) over 12 % in 2018.1 But there is a limited number of literatures reporting on PbS QD based solar working in low photon energy region( 1.0 eV). Our recent study revealed that PbS QD/ZnO nanowire(NW) solar cells were able to convert a wide range of solar energy to electricity. However, the free carrier absorption of the transparent conductive oxide(FTO: F-doped SnO) in infrared region cause a non-negligible energy loss of the incident solar energy to be absorbed by the PbS QD layer. In this presentation, we constructed infrared PbS QD/ZnO NW solar cells having the first exciton absorption peak at 1560 nm(0.8 eV) and successfully improved the spectral sensitivity in infrared region by employing highly infrared transparent 1% Ta-doped SnO(TTO) electrodes. The EQE reached its maximum value of 47% at 1560 nm. The integrated photo-current density obtained from the EQE spectrum over 38 mAcm for full solar spectrum(Fig.1). The solar cell installed with an 870 nm sharp-cut filter yielded a PCE of 2.02 %(J=14.8 mAcm;Vc=0.285 V;FF=47.9 %) under a filtered one-sun illumination. The PCE is the highest efficiency reported to date for solution processed solar cells working in the infrared region. Based on these results, we will discuss the potential of PbS QD/ZnO NW solar cells toward the bottom subcells of tandem solar cells.