Highly efficient organic tandem solar cell with a SubPc interlayer based on TAPC:C70 bulk heterojunction

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic photovoltaic (OPV) cells offer potential for low-cost, flexible solar energy.
• Tandem OPV architectures are explored to enhance power conversion efficiency (PCE).
• Efficient charge extraction and minimized series resistance are critical for high-performance OPVs.

Purpose of the Study:

• To develop a high-efficiency small molecule tandem organic photovoltaic (OPV) cell.
• To investigate the impact of a boron subphthalocyanine chloride (SubPc) interlayer on OPV performance.
• To understand the mechanisms behind performance enhancement in the tandem OPV cell.

Main Methods:

• Fabrication of a tandem OPV cell with two identical mixed active layers (C70:5 wt%TAPC).
• Incorporation of a thin boron subphthalocyanine chloride (SubPc) interlayer between subcells.
• Performance characterization including power conversion efficiency (PCE), short-circuit current, open-circuit voltage, and series resistance.

Main Results:

• Achieved a high power conversion efficiency (PCE) of 7.27%.
• The SubPc interlayer significantly increased short-circuit current and open-circuit voltage.
• The SubPc interlayer effectively reduced the series resistance of the tandem cell.
• The cell's response was primarily driven by C70 absorption.

Conclusions:

• The SubPc interlayer is crucial for enhancing the performance of C70-based tandem OPVs.
• Improved hole extraction at the anode, due to band bending at interfaces, contributes to high PCE.
• This work demonstrates a promising strategy for developing efficient small molecule tandem OPVs.