Photovoltaic bulk heterojunctions with interpenetrating network based on low band gap, synthetic, p-type conjugated poly(indenofluorene) as electron donor (D) near IR chromophore and soluble derivative of electron-accepting (A) buckminsterfullerene C-61 were produced. D/A ratios 1:1 and 2:1 and Al cathode were used. Additional n-type tetrafluoro-7,7,8,8-tetracyanoquinodimethane dopant and low work function Yb cathode were used in order to strengthen the conductivity of percolation paths and force an increased internal electric field. Use of the dopant slightly improved the current performance of the cells.