# Investigation of the Use of Cu as Top Electrode in Polymer Solar Cells

## TL;DR

This paper explores using copper as a low-cost top electrode in polymer solar cells and evaluates its performance and stability.

## Contribution

The study demonstrates copper's viability as a cost-effective top electrode in polymer solar cells under controlled conditions.

## Key findings

- Devices achieved a power conversion efficiency of 2.86% with a fill factor of 68%.
- Efficiency decreased by 23% under glovebox conditions over 12 weeks.
- Device degradation is linked to oxygen and moisture effects on the copper electrode.

## Abstract

Reducing electrode-related costs is an important step toward the large-scale commercialization of polymer solar cells. In this study, Cu is investigated as a low-cost top electrode in inverted polymer solar cells with the architecture ITO/ZnO/P3HT:PCBM/MoO3/Cu. The fabricated devices achieved a maximum power conversion efficiency (η) of 2.86%, with an open-circuit voltage (Voc) of 610 mV, a short-circuit current density (Jsc) of 6.90 mA cm−2, and a fill factor (FF) of 68%. Long-term stability tests were carried out over a period of 12 weeks under glovebox, desiccator, and ambient room conditions, during which efficiency decreases of 23%, 53%, and 78% were observed, respectively. Structural and spectroscopic analyses suggest that device degradation is closely associated with O2- and moisture-induced effects on the Cu electrode. The results demonstrate that Cu can be effectively employed as a top electrode in polymer solar cells under controlled environmental conditions, highlighting its potential as a cost-effective electrode material for polymer solar cell applications.