Organic/inorganic hybrid solar cells combine the low-cost and processability characteristics of polymers with the environmental stability and light absorption properties of inorganic semiconductors. A number of materials and structures for fabricating these devices are currently under investigation. The present work describes the fabrication and characterization of a set of hybrid solar cells in various multilayer arrangements. These cells are based on the abrupt heterojunction concept, using inorganic n-type semiconducting amorphous silicon (a-Si(n)) as electron acceptor, and organic hole conducting poly(3-hexyltheophene) (P3HT) polymer as electron donor. Alternatively, P3HT:PCBM blend was used as the organic material in other devices. The cells were fabricated over ITO coated glass substrates by RF sputtering of a thin (10-30 nm) film of silicon. A 30-50 nm thick layer of P3HT or blend was spin-coated from a solution in chlorobenzene in the stacked ITO/a-Si(n)/P3HT/Ag structure (A) and ITO/a-Si(n)/P3HT:PCBM/Ag structure (B). Top contacts of Ag were formed by thermal evaporation of thick silver film. A third structure (C), with the ITO/PEDOT/P3HT/a-Si(n)/Ag sequence, was also studied. Structures A and B showed heterojunction behavior, yielding open circuit voltage (Voc) of ~0.48 V and 0.44 V, respectively. Structure C showed diode like dark characteristics, but poor photo-response. Performance of these cells was analyzed by means of their I-V characteristics, impedance and capacitance/voltage measurements.