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 × 10−4 cm2 V−1 s−1 to 7.61 × 10−4 cm2 V−1 s−1 with the hole/electron mobilities (µh/µe) 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.