The photoresponse of polymer field effect transistors (PFETs) based on the 2,5- bis(dibutylaminostyryl)-1,4-phenylene-b-alkyne-b-1,4-bis(2-ethylhexyl)benzene terpolymer (BAS-PPE) is investigated. BAS-PPE is a photoluminescent conducting polymer with a bandgap of 2.25 eV. The BAS-PPE PFETs were fabricated using an open coplanar configuration and light is illuminated onto the top side of the PFETs. A sweep of VDS demonstrates that IDS saturation is suppressed during illumination, which suggests that pinch-off can not be reached since the injection of photo-generated carriers continues unabated. Also, with incident light, the channel can not be turned off, even at high positive gate biases, due to the accumulation of photo- generated carriers. A sweep of VDS also shows that BAS-PPE can act as a p-type polymer and favors hole injection and transport.