Amorphous Spiro-OMeTAD Prepared Flexible Films with Surface Engineering Boost Ternary Resistive Memory Yield to 86%

Organic ternary resistive memories can greatly improve the information density and thus are being extensively explored. However, the effective ternary device yield remains too low (usually <50%) for potential industrialization despite that laborious formula innovations have been attempted to improve molecular conjugation and crystallinity of the active materials. Here, it is demonstrated that using solvent and surface engineering, the devices based on amorphous 2,2 ',7,7 '-tetrakis[N,N-di(4-methoxyphenyl) amino]-9,9 '-spirobifluorene (Spiro-OMeTAD) achieve a ternary device yield of 86%, which is the highest among all reported to date. Spiro-OMeTAD is amorphous in the thin film and has a pristine device yield of 42%, challenging the concept that conjugated molecules or polymers should be employed in resistive memories. In addition, by optimizing the film thickness and surface smoothness through solvent and surface engineering, Spiro-OMeTAD on octyl phosphonic acid-modified indium-tin-oxide (ITO) glass has much smoother surface, and the ternary device yield is elevated to 86%. The amorphous nature of Spiro-OMeTAD also enables polyethylene terephthalate-ITO/Spiro-OMeTAD/Al device to display outstanding flexibility with no significant decline of ternary device yield undergo 10 000 bending cycles and 72 degrees bending degree. The result stimulates more material selections and paves the way for practical application of resistive memories.