A phosphosilicate polymer spin-on glass dopant has been adapted to produce a screen printable N-type diffusion pastes using different types of nanoparticles as functional additives to quantitatively change the doping strength of the paste. Strong qualitative and quantitative differences in the resulting phosphorous concentration profiles after diffusion have been found between different compositions. Not only is an intermediate doping level obtainable if silicon nanoparticles are used instead of silica but also a shallower dopant depth is also achieved. The electrical quality of the layer formed by diffusing phosphorus into the surface of a P-type silicon wafer has been investigated by the fabrication and testing of P-N junction solar cells. The devices exhibit diodelike current–voltage (IV) characteristics with open-circuit voltages of 0.437 V and 0.523 V and short-circuit current densities of 1.88 mA/cm2 and 4.78 mA/cm2 indicating a low doping level of the cell emitter and a relatively high series resistance of the junction.