Diffusion-agent composition, method for forming impurity-diffusion layer, and solar cell

A diffusing agent composition used to form an impurity-diffusing agent layer on a semiconductor substrate, comprising:

• a borate ester (A);
• a polyhydric alcohol (B) expressed by the following general formula (1);
• and
• an alkoxysilane compound (C).
• [In the general formula (1), k represents an integer of 0 to 3, m represents an integer of 1 or more, and R2 and R3 each individually represent a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, or a hydroxyalkyl group having 1 to 5 carbon atoms. When there are a plurality of R2s and R3s, the plurality of R2s and R3s may be the same or different from one another. When k is 2 or more, the plurality of R2s and R3s always contain one or more hydroxyl group or hydroxyalkyl group having 1 to 5 carbon atoms. R4 and R5 each individually represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.]