Enhanced and Balanced Carrier Mobility Via n-Type SnS Dopant Enables High-Performance Non-Fullerene Organic Solar Cells

The unbalanced electron-hole mobility is the major bottleneck for boosting the photovoltaic performance of organic solar cells. In this study, 2D n-type inorganic semiconductor material tin sulfide (SnS) is prepared and introduced into the PM6:Y6 bulk heterojunction organic solar cells to improve photovoltaic performance. The incorporation of SnS promotes Y6 crystallization, and renders the face-on orientation of Y6 molecules dominant. The improved active layer morphology suppresses carrier recombination and strengthens the electron transport. The electron mobility increases significantly from 4.71 x 10(-4) cm(2) V-1 s(-1) to 7.61 x 10(-4) cm(2) V-1 s(-1) with the hole/electron mobilities (mu (h)/mu (e)) value reducing from 1.67 to 1.11. With enhanced and balanced carrier mobility, the open-circuit voltage, short-circuit current density and fill factor of the SnS-doped PM6:Y6 organic solar cells are improved simultaneously, and the power conversion efficiency is boosted from 16.66 to 18.50%. Additionally, the SnS doped devices exhibit better thermal and storage stability. The improved photovoltaic performance is further verified in PM6:L8-BO and D18:Y6 based organic solar cells. This work demonstrates that n-type SnS dopant is an efficient and universal method to improve photovoltaic performance of non-fullerene organic solar cells.