Photovoltaics (IEK-5)

Distinguishing between recombination and charge extraction is a challenge for solar cell characterization. Using the rise and decay of the transient photovoltage after a laser pulse can be a solution for the problem.

Ravishankar et al. developed a model to describe the frequency domain response of perovskite solar cells with an emphasis on the role of transport layers. Application to experimental data identifies that measured time constants are limited by charge carrier extraction rather than by recombination.

Energetic disorder reduces solar cell efficiencies but is difficult to characterize. Hartnagel et al. perform a comparative study of different methods to quantify disorder and show how method-specific bias in the resulting values can modify the results.

The diffusion length is frequently used to explain poor charge collection in halide perovskite solar cells. However, in the presence of only moderately conductive charge transport layers, non-linear series resistances can modulate the carrier density and thereby the recombination losses even if transport in the perovskite itself is nearly perfect.

All-inorganic perovskites, which replace the organic A-site cation with inorganic elements, are promising candidates for photovoltaics due to their improved stability relative to hybrid perovskites. Here Yuan et al. review the state-of-the-art of all-inorganic perovskites for photovoltaic applications by performing detailed meta-analyses of key performance parameters on the cell and material level.

Lifetimes of charge carriers are a key metric to quantify recombination in solar cells. However, due to different measurement modes, the word “lifetime” might mean many different things thereby making quantitative comparisons impossible. Here a consistent model for transient spectroscopy analysis is shown to solve this problem.

Recombination is one of the major loss processes in any solar cell. Solar cell optimiation therefore relies on characterization techniques to quantify recombination. Here a new approach is proposed based on voltage dependent photoluminescence.

Capacitance measurements are commonly used to estimate defect densities in a solar cell. Ravishankar et al. show that for a solar cell comprising of multiple layers, the traditional analysis of capacitance data is erroneous because the capacitance response of the absorber layer is hidden by overlapping responses from the other layers.

Coupling of photovoltaic (PV) devices with energy storage such as batteries is essential to stabilize PV electricity supply.

with perovskite solar modules and sodium-ion batteries

The outcome of this artificial photosynthesis research project consists of an autonomous device able to convert CO2 and H2O to fuels using sunlight.

EU invests €3.5M in a project to convert carbon and nitrogen emissions into valuable resources

Comparing efficiencies of solar cells for indoor applications is challenging due to the variety of light sources and lack of standards. Lübke et al. show a solution to this problem that allows comparison of data measured with a variety of different light sources.

A properly chosen PV-battery pair can maintain a high degree of internal power coupling even under variable irradiance and load without MPPT electronics.

Distinguishing between recombination and charge extraction is a challenge for solar cell characterization. Using the rise and decay of the transient photovoltage after a laser pulse can be a solution for the problem.