Liquid phase crystallized silicon on glass with a thickness of (10–40) μm has the potential to reduce material costs and the environmental impact of crystalline silicon solar cells. Recently, wafer quality open circuit voltages of over 650 mV and remarkable photocurrent densities of over 30 mA/cm2 have been demonstrated on this material, however, a low fill factor was limiting the performance. In this work we present our latest cell progress on 13 μm thin poly-crystalline silicon fabricated by the liquid phase crystallization directly on glass. The contact system uses passivated back-side silicon hetero-junctions, back-side KOH texture for light-trapping and interdigitated ITO/Ag contacts. The fill factors are up to 74% and efficiencies are 13.2% under AM1.5 g for two different doping densities of 1 · 1017/cm3 and 2 · 1016/cm3. The former is limited by bulk and interface recombination, leading to a reduced saturation current density, the latter by series resistance causing a lower fill factor. Both are additionally limited by electrical shading and losses at grain boundaries and dislocations. A small 1 × 0.1 cm2 test structure circumvents limitations of the contact design reaching an efficiency of 15.9% clearly showing the potential of the technology.

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Potential‐induced degradation (PID) is a solar cell‐related degradation mechanism due to high potential difference in a photovoltaic (PV) module between the solar cells and its grounded frame. This type of degradation is well known for silicon PV; however, for perovskites it has not been thoroughly researched yet. Herein, the PID of perovskite solar cells is investigated for bias voltages of ±500 V, half of the currently used system voltage, and ±1000 V with regular I–V and electroluminescence measurements during the test. The devices show a high PID resistance under applied bias of ±500 V, far exceeding the recommended guidelines for silicon PV. However, for the bias voltage of –1000 V a rapid degradation is observed due to the ingress of sodium ions from the glass substrate as confirmed by the time‐of‐flight secondary ion mass spectrometry measurements of spatial and depth distribution of elements in solar cells. Positively biased devices show no degradation due to high voltage exposure. These results show promising signs that perovskite solar cells are PID proof for current PV system designs.

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The electroluminescence (EL) imaging process of small area solar cells is investigated in detail to expose optical and electrical effects that influence image acquisition and corrupt the acquired image. An approach to correct the measured EL images and to extract the exact EL radiation as emitted from the photovoltaic device is presented. EL images of circular cadmium telluride (CdTe) solar cells are obtained under different conditions. The power-law relationship between forward injection current and EL emission and a negative temperature coefficient of EL radiation are observed. The distributed Simulation Program with Integrated Circuit Emphasis (SPICE®) model of the circular CdTe solar cell is used to simulate the dark J-V curve and current distribution under the conditions used during EL measurements. Simulation results are presented as circularly averaged EL intensity profiles, which clearly show that the ratio between resistive parameters determines the current distribution in thin-film solar cells. The exact resistance values for front and back contact layers and for CdTe bulk layer are determined at different temperatures, and a negative temperature coefficient for the CdTe bulk resistance is observed.