A precursor solution for semiconducting Si called liquid Si (liq‐Si) is synthesized, and semiconducting Si is inkjet‐printed. Satisfactory inkjet discharge is achieved using liq‐Si consisting of liquid‐phase polysilane with an average molecular weight of 2500 g mol−1. The printed liq‐Si is converted into amorphous Si by heating at 400 °C. The resulting Si film has a flat surface with a root‐mean‐square roughness of 0.8 nm. These results are extended to n‐ and p‐type Si films by synthesizing liq‐Si chemically doped with P and B compounds, respectively. Liq‐Si inkjet printing produces Si patterns without using traditional photolithography processes, opening up the field of printed Si electronics.

Although little is known about the reaction mechanism between cyclopentasilane (CPS: cyclic Si5H10) and borane (BH3), the reaction product is known to be a liquid precursor for p-type semiconducting Si....

Front Cover: In article number 2000362 by Takashi Masuda and co‐workers, a precursor solution for semiconducting Si called liquid‐Si is synthesized and printed by an inkjet method. Well‐defined printed patterns are converted into amorphous or polycrystalline Si by heat treatment. The Si printing technology is also extended to p‐ and n‐type Si film by synthesizing liquid‐Si chemically doped with B and P compounds, respectively.