Correlating carrier lifetime with device design and photovoltaic performance of perovskite solar cells

Efficient electron transport layer-free perovskite solar cells (ETL-free PSCs) are promising designs because they offer low-cost, simpler device configuration and greatly promote the large area flexible application of PSCs. Meanwhile, compared to traditional PSCs with ETL, the development of ETL-free PSCs is hindered by their low performance due to serious interfacial energy loss. Herein, we reveal that ETL-free devices with relatively low carrier lifetimes of perovskite films exhibit more substantial photogenerated carrier loss, resulting in a lower electron-injection rate at the FTO (fluorine-containing tin oxide)/perovskite interface, which is mainly responsible for the performance loss. Moreover, we demonstrate that improving the carrier lifetimes of perovskite films can remedy the poor carrier extraction efficiency at the FTO/perovskite interface through three typical perovskite films. Similarly, for all-inorganic perovskite with lower carrier lifetime and hole transport layer-free devices, prolonging carrier lifetime may be an important measure to improve the device performance. Benefiting from this discovery, increasing the carrier lifetime of the perovskite films can counterbalance the inferior device interfaces, endowing the ETL-free PSCs with high performance close to that of the ETL devices. Our research provides insights into ETL-free PSCs and offers opportunities for high-performance ETL-free PSC device design.

Automated summary

Efficient electron transport layer-free perovskite solar cells (ETL-free PSCs) offer low-cost and simpler device configurations, but suffer from low performance due to interfacial energy loss. Improving carrier lifetimes of perovskite films can enhance carrier extraction efficiency at the FTO/perovskite interface, leading to high performance comparable to ETL devices. This research provides insights into high-performance ETL-free PSC device design.