Vacuum-deposited interconnection layers for tandem solar cells

•Different types of interconnection layers for tandem solar cells were investigated.•Spatial positions of sub-cells were designed to balance the photocurrent.•Highly efficient tandem cell with efficiency up to 7.4% were demonstrated.

Two different types of vacuum-deposited interconnection layers (ICLs) were investigated for tandem solar cells: (1) a pure metal oxide and (2) an organic matrix doped with conductive dopants. The optical and electrical properties of these ICLs were systematically studied and compared. Taking the characteristics of ICLs into consideration, optical design methodology for balancing the photocurrent of each sub-cell in the tandem cell is presented. According to the design, highly efficient small-molecule tandem solar cells with power conversion efficiencies up to 7.3%–7.4% were experimentally demonstrated in both devices utilizing pure metal oxide and organic matrix ICLs.

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