An organic photovoltaic (OPV) device comprises a first arrangement of at least one OPV cell, and a second arrangement of at least one OPV cell, wherein the first and second arrangements are connected in parallel. An organic photovoltaic device comprises a substrate, a first and second electrodes above the substrate, and a heterojunction between the electrodes, comprising a first and second regions, wherein at least a portion of the heterojunction is lightly doped, wherein a conductivity dopant is covalently tied to a host within the first or second regions.

A photovoltaic device includes a first photovoltaic cell assembly and a second photovoltaic cell assembly. The first photovoltaic cell assembly includes a first group of thin-film photovoltaic cells electrically connected in series and a second group of photovoltaic cells electrically connected in series. The second photovoltaic cell assembly includes a third group of thin-film photovoltaic cells electrically connected in series and a fourth group of photovoltaic cells electrically connected in series. The first group and the third group have a common electrode. An electrical connection of the first photovoltaic cell assembly and the second photovoltaic cell assembly is configured to match a voltage at maximum power (Vmp) generated by the first group and the third group and by the second group and the fourth group.

Solar cell modules and methods of fabrication are described. In an embodiment, a pair of tandem solar cells are bonded together along a contact ledge of a first tandem solar cell using a solid electrically conductive bonding material.