Balancing Charge Extraction for Efficient Back‐Contact Perovskite Solar Cells by Using an Embedded Mesoscopic Architecture

Abstract As the performance of organic–inorganic halide perovskite solar cells approaches their practical limits, the use of back‐contact architectures, which eliminate parasitic light absorption, provides an effective route toward higher device efficiencies. However, a poor understanding of the underlying device physics has limited further performance improvements. Here a mesoporous charge‐transporting layer is introduced into quasi‐interdigitated back‐contact perovskite devices and the charge extraction behavior with an increased interfacial contact area is studied. The results show that the incorporation of a thin mesoporous titanium dioxide layer significantly shortens the charge‐transfer lifetime and results in more efficient and balanced charge extraction dynamics. A high short‐circuit current density of 21.3 mA cm –2 is achieved using a polycrystalline perovskite layer on a mesoscopic quasi‐interdigitated back‐contact electrode, a record for this type of device architecture.