Interface Modification of Tin Oxide Electron-Transport Layer for the Efficiency and Stability Enhancement of Organic Solar Cells

A small molecular phenanthroline derivative Phen-NaDPO (3-[6-(diphenylphosphinyl)-2-naphthalenyl]-1,10-Phenanthroline) to modify tin oxide (SnO2) electron-transport layer (ETL) in organic solar cells is employed. Quantum chemistry calculations and experimental results show that Phen-NaDPO can interact with SnO2, thereby effectively passivating the surface defects, reducing the work function and improving the electrical conductivity of SnO2, leading to more efficient electron extraction and transport in the organic solar cells (OSCs). Moreover, upon the Phen-NaDPO modification, the decreased surface energy of SnO2 ETL accounts for enhanced exciton dissociation and charge transport, due to the more ordered molecular organizations of the active layers. Consequently, the inverted OSCs involving Phen-NaDPO/SnO2 ETLs exhibit an enhanced power conversion efficiency of 17.06% (PM6:Y6) and 18.31% (PM6:L8-BO), which is the highest efficiency for SnO2 ETL-based binary solar cells to date. Furthermore, the devices based on Phen-NaDPO/SnO2 ETL show better device stability (storage stability, photostability and humid stability), with T80 exceeding 200 h encapsulated under light irradiation and 400 h without encapsulation in high-humidity ambient condition. These results demonstrate that the modification of SnO2 using wide-band highly stable conjugated small molecules is very promising for simultaneously improve the efficiencies and device stability of OSCs. This study introduces a novel method employing small molecule Phen-NaDPO to modify SnO2 for highly efficient and stable OSCs, attaining an impressive PCE of 18.31% in binary cells. The Phen-NaDPO-modified devices demonstrate exceptional stability in diverse environmental conditions, including extended light exposure and high humidity, with T80 exceeding 200 h in light and 400 h in high humidity.image

Automated summary

This study introduces the use of a small molecule Phen-NaDPO to modify the tin oxide electron-transport layer in organic solar cells. The modification effectively passivates surface defects, reduces work function, and improves electrical conductivity, leading to enhanced electron extraction and transport. The modified devices also exhibit exceptional stability in various environmental conditions.