We have recently shown that specific and stable n or p doping may be obtained on poly(paraphenylene) providing moderate implantation conditions with appropriate ions are used. Here we describe a pn+ -junction made in intrinsic insulating poly(paraphenylene) (σ <10−12 Ω −1 cm−1) by implantation (E ⋍ 50keV) of alkali metal ions (essentially caesium for n doping) and halogen (iodine for p doping).