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Lead iodide (PbI 2) is a semiconductor with extensive use as an active layer for X-ray detectors and as a precursor for perovskite solar cells. Here we present a low vacuum method to obtain very uniform PbI 2 films with full substrate coverage. This method consists in the sublimation of PbI 2 inside a hot zone and its transport by an Ar flow to a substrate held at a controlled temperature. Using scanning electron microscopy combined with focused ion beam and X-ray diffraction we studied the morphology and crystallographic structure of the PbI 2 films with different deposition parameters: substrate and source evaporation temperature, deposition time and substrate material. At high substrate temperature (80ºC) and low evaporation temperature (310ºC) onto a glass sample, we obtained dense and smooth PbI 2 films showing hexagonal crystals, or platelets, stacked parallel to the substrate. The choice of the substrate material has a significant impact on the film morphology yielding porous-like structures with voids within the films for some substrates. A bandgap E g = 2.42 eV and Urbach energy

Even within the simplest real solar cell model, the exact value of the fill factor (FF) is only computable by numerical calculations. Here, we perform approximations to the power–voltage curve given by the one‐diode model with series and shunt resistance losses, obtaining explicit expressions for the voltage and current at the maximum power point, and thus an explicit approach for the FF. Over a broad range of possible solar cell parameters, including cells where the impact of shunt losses on the fill factor is not negligible, the approximate equations yield relative errors typically around 1%. The equations are applied to explore the dependence of FF on alternative buffer material thickness of organic solar cells, and to investigate the incidence of shunt and series resistance losses on the FF of Cu(In,Ga)Se2 solar cells under indoor illumination conditions. Copyright © 2012 John Wiley & Sons, Ltd.