In a photovoltaic cell having a photovoltaically active semiconductor material constituted by a plurality of metals or metal oxides, the photovoltaically active material is selected from a

• p- or n-doped semiconductor material constituted by a ternary compound of the general formula (I)

  Me_xS^A_yS^B_z  (I)

  with

• Me=Al, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu or Ag,
• S^A, S^B=B, C, Si, Ge, Sb, Se or Te,
• where S^A and S^B respectively come from different groups of the periodic table,
• x, y, z are independent of one another and can take values from 0.01 to 1,
• and where the proportion by weight of S^A and S^B together is no more than 30%, expressed in terms of the total semiconductor material,

  or a mixed oxide of the general formula (II)

  ##EQU1##

  with

• Me=Fe, Cu, V, Mn, Sn, Ti, Mo, W
• n=integer from 1 to 6,
• a=1 or 2,
• f=number from 0.2 to 5,
• k=number from 0.01 to 2,

  u+v+w+x=1.