Technology Computer Aided Design modeling is used to examine the performance under light concentration of a 4-J solar cell Ge-based that includes a 1-eV MBE-grown dilute nitride subcell. The 1-eV solar cell is modeled and examined by using material parameters extracted from detailed electro-optical characterization prior to be included into a multijunction structure. The modelling reveals the impact of the electric field-assisted collection in the performance of single junction solar cells and its effect when included in a 4-Junction solar cells. This effect is responsible for the lower FF (~15% lower) in the 4J when including the dilute nitride subcell, especially if it limits the photocurrent. Finally, an optimization procedure based on dilute nitrides with higher material quality is performed resulting in a 4-Junction solar cell with an efficiency of 47% for concentrations between 1000-2000 suns direct terrestrial spectrum.

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CdTe-based solar cells exhibiting 19% power conversion efficiency were produced using widely available thermal evaporation deposition of the absorber layers on SnO 2 -coated glass with or without a transparent MgZnO buffer layer. Evaporating CdSe and CdTe sequentially by thermal evaporation and subsequent CdCl 2 annealing establishes efffective CdSeTe band grading as well as dense, large-grain films. These results show that high-performance II−VI photovoltaics can be made by inexpensive, commercially available evaporation systems without the need to build customized equipment, enabling CdTe photovoltaics research and manufacturing to be more accessible to the broader photovoltaics community.

Temperature coefficients for maximum power (T PCE), open circuit voltage (V OC), and short circuit current (J SC) are standard specifications included in data sheets for any commercially available photovoltaic module. To date, there has been little work on determining the T PCE for perovskite photovoltaics (PV). We fabricate perovskite solar cells with a T PCE of −0.08 rel %/°C and then disentangle the temperature-dependent effects of the perovskite absorber, contact layers, and interfaces by comparing different device architectures and using drift-diffusion modeling. A main factor contributing to the small T PCE of perovskites is their low intrinsic carrier concentrations with respect to Si and GaAs, which can be explained by its wider band gap. We demonstrate that the unique increase in E g with increasing temperatures seen for perovskites results in a reduction in J SC but positively influences V OC. The current limiting factors for the T PCE in perovskite PV are identified to originate from interfacial effects.

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The thermal annealing of nitrogen related traps in p-type InGaAsN and GaAsN is investigated by deep level transient spectroscopy (DLTS). Upon annealing, an apparent recovery of the photovoltaic properties correlates with changes in the DLTS data observed for InGaAsN and GaAsN diodes and solar cells, revealing that a nitrogen related E1 (EC−0.20eV) center has an important role in governing the solar cell performance. The large electron capture cross section (∼8.9×10−15cm2) of this center indicates that this defect may act as an efficient recombination center. Therefore, its complete removal by annealing or by some other process is essential for the high performance of GaInAsN solar cells. The internal quantum efficiency data were modeled to quantify the change in material properties associated with this improvement upon annealing. Annealed cells with indium impurity (InGaAsN) show a slightly higher photoresponse, which could be due to low scattering caused by In–N pair formation after annealing.

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