Toward improved stability of nonfullerene organic solar cells: Impact of interlayer and built-in potential

Improved efficiency and stability of the organic solar cells (OSCs) are the critical considerations for practical applications. The interface between the interlayer and bulk heterojunction has recently been shown as one of the weak links associated with the degradation in the nonfullerene acceptor (NFA)-based OSCs. It shows that the removal of the interfacial chemical reactions between the 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (INCN) moieties in NFA and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) hole extraction layer (HEL) is desired for enhancing the device stability. In this work, we show that the use of a bilayer MoO₃/antimonene HEL favors the operational stability in OSCs through maintaining a high built-in potential and suppression of an undesired interfacial reaction between INCN moieties in NFA and the PEDOT structures in PEDOT:PSS. A power conversion efficiency of 16.68% is also obtained for the OSCs with a bilayer MoO3/antimonene HEL, prepared using a blend system of PM6:Y6, demonstrating its suitability for high-performance OSCs.