Monomeric or polymeric compounds comprising at least one moiety of the formula (Ia) wherein X is CR, where R is H or a substituent as defined in claim
1,
or is another ketopyrrole moiety e.g. of the formula (1
b
) or (1
c
) with this moiety and all other symbols are as defined in claim
1,
show good solubility in organic solvents and excellent film-forming properties. In addition, high efficiency of energy conversion, excellent field-effect mobility, good on/off current ratios and/or excellent stability can be observed, when the polymers according to the invention are used in semiconductor devices or organic photovoltaic (PV) devices (solar cells).