Electroactive and Self‐healing Polyurethane Doped Tin Oxide Interlayers for Efficient Organic Solar Cells†.

Comprehensive Summary Tin oxide (SnO2) has been widely used as an electron transport layer (ETL) in optoelectronic devices. However, there are numerous surface or bulk defects in SnO2, working as charge recombination centers to degrade device. Here, an electroactive and self‐healing polyurethane (PHNN) was designed by integrating conjugated unit – naphthalene diimide (NDI) into a typical polyurethane backbone. Numerous hydrogen bonds and π interactions in PHNN work as non‐covalent interactions to endow this polymer with superior self‐healing properties. PHNN contains lots of aliphatic amine and carbonyl groups, which effectively passivate the defects in SnO2. The π stacking of NDI units will facilitate electron delocalization, endowing PHNN with electrical activity compared with traditional polyurethane. Doping SnO2 with PHNN can improve the conductivity and reduce the work function of SnO2 layer, which is conducive to efficient charge extraction and transport. Using PHNN doped SnO2 as ETL for PM6: Y6 and PM6: BTP‐eC9 based inverted organic solar cells can achieve a high efficiency of 17.16% and 17.51%, respectively. Devices containing doped SnO2 ETL show significantly improved efficiency and stability. Thus, the electroactive polyurethane doped SnO2 interlayers show high performance interfacial modification to align energy‐levels in solar cell devices, which have promising applications in organic electronics. [ABSTRACT FROM AUTHOR]