P‐type Semiconducting Polymers as Photocathodes: A Comparative Study for Optobioelectronics

Abstract Recent studies have shown that p‐type polymeric semiconductors enable a new type of wireless, optically triggered interface with cells and tissues. Poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) has already been used to create such optobioelectronic interfaces, producing reactive oxygen species hydrogen peroxide act as messengers in biological systems impact cell signaling proliferation. However, the use P3HT biomedical in‐vivo applications is limited its optical absorption does not match tissue transparency window. This paper compares performance two low band‐gap polymers commonly employed high‐performance organic solar cells, namely Poly[[4,8‐bis[5‐(2‐ethylhexyl)‐2‐thienyl]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl]‐2,5‐thiophenediyl[5,7‐bis(2‐ethylhexyl)‐4,8‐dioxo‐4H,8H‐benzo[1,2‐c:4,5‐c′]dithiophene‐1,3‐diyl]] (PBDB‐T) Poly({4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl}{3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b] thiophenediyl}) (PTB7). Their photogeneration capabilities are quantified physiological‐like conditions through photocurrent analysis assay, finding superior generation better H 2 O yield PTB7 compared other polymers. Spectroscopic structural investigations compare differences by comparing their energy levels at electrochemical morphologies. Finally, biocompatibility tested both dark illuminated effective in‐vitro intracellular ROS production demonstrated. These findings provide insight into physico‐chemical properties crucial for development novel, less invasive, operated bioelectronic interfaces.