Mechanically Stacked, Two-Terminal Graphene-Based Perovskite/Silicon Tandem Solar Cell with a Stabilized Efficiency of 25.9%

Abstract

Perovskite/silicon tandem solar cells represent an attractive strategy to push the market-leading crystalline silicon technology beyond its theoretical limit, maintaining low module costs. Record-high efficiency silicon heterojunction cells with a micrometre-sized pyramid textured front-surface hinder high-temperature and low-cost solution processing of the top-cell in a monolithic architecture. We present a mechanically stacked two-terminal perovskite/silicon tandem device, allowing independent fabrication and optimization of the sub-cells, subsequently coupled by contacting the back-electrode of the mesoscopic perovskite top-cell with the texturized and metalized front-contact of the silicon bottom-cell. Our champion device exhibits a stabilized efficiency of 25.9% over a 1.43 cm2 active area, achieved by optically engineering the hole-selective layer/rear-contact structure to minimize the optical losses, and improving the electrical performance with a graphene-doped mesoporous electron-selective layer. This represents a simple path toward fabricating tandem devices overcoming the limit of single junction solar cells and with a competitive levelized cost of energy.