Cross-linkable alternating copolymer featuring dibenzothiophene-S,S-dioxide segment applicable for organic optoelectronic devices with good stability

The cross-linking strategy has been applied to enhance the photoelectric conversion efficiency and device stability of polymer light-emitting diodes (PLEDs) or polymer solar cells (PSCs). However, the application of cross-linkable polymers containing dibenzothiophene-S,S-dioxide segment as an active layer component or active layer additive in optoelectronic devices has garnered little attention. In this work, a feasible method for improving the photoelectric conversion efficiency and device stability of PLEDs and PSCs is demonstrated by utilizing a cross-linkable alternating copolymer containing dibenzothiophene-S,S-dioxide segment, which named as poly[(9,9′-bis-(3- ethyl(oxetane-3-ethyloxy)-hexyl)-fluorene-2,7-yl)-alt-(2,8-bis(octyloxy)-dibenzothiophene-S,S-dioxide-3,7-yl)] (CLPFSO), as the emitting layer in PLED or as an active layer additive in PSC. The polymer CLPFSO was procured through Suzuki polymerization process and could be cross-linked via thermal treatment. The PLED, structured as ITO/PEDOT:PSS/CLPFSO/CsF/Al with CLPFSO as the emitting layer, achieved peak luminance efficiency (LEmax) of 3.6 cd/A and sustained 78% of its initial LEmax across 30 days. The inverted PSC consisting of ITO/ZnO/PTB7-Th:PC71BM:CLPFSO/. MoO3/Ag with CLPFSO as an active layer additive showed a maximum PCE value of 9.51% and maintained 81% of its initial PCE over a span of 30-day period. The findings of this study offer a valuable viewpoint towards enhancing the efficiency and the stability of PLEDs and PSCs.