Nitroxide Radical Conjugated Polymers: Synthesis and Application as Solid Additives for High‐Efficiency Organic and Perovskite Solar Cells

ABSTRACT A series of nitroxide radical conjugated polymers (PBDT‐NOx), specifically named PBDT‐NO100, PBDT‐NO60, PBDT‐NO40, PBDT‐NO20, and PBDT‐NO5, are synthesized via palladium‐catalyzed Stille coupling polymerization. These polymers are accordingly constructed from 4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b’]dithiophene‐2,6‐diyl) (BDT), 1,3‐bis(5‐bromothiophen‐2‐yl)‐5,7‐dioctyl‐4H,8H‐benzo[1,2‐c:4,5‐c’]dithio‐phene‐4,8‐dione (BDD), and 1,4‐bis(4‐oxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl)phthalate (BTMP), with their molar feed ratios systematically varied from 50:0:50 to 50:45:5. The chemical structures, molecular weights, and optoelectronic properties are characterized. Upon the addition of the PBDT‐NOx as additives, the power conversion efficiencies (PCEs) of the PM6:Y6‐based non‐fullerene‐based organic solar cells (NFAs‐OSCs) are increased from 15.62% to 16.71%–17.04%, contributed by the improvement of the electron and hole mobility, reduced charge carriers' recombination, and mitigation of the non‐radiative energy loss, thus leading to PCE improvements of the NFAs‐OSCs. Furthermore, the utilization of the representative PBDT‐NO60 as a solid additive for the hole transporting layers (HTL) of Spiro‐OMeTAD with Li‐TFSI for the Cs 0.05 Rb 0.05 (FA 0.83 MA 0.17 ) 0.90 Pb(I 0.95 Br 0.05 ) 3 based perovskite of solar cells (PSCs), which result in the improvement of the hole mobility of HTL, reduced carrier recombination, and enhanced carrier extraction, therefore leading to PCE improvements from 19.31% to 21.17% the PSCs, are supported an discussed.