Energy conversion efficiency losses and limits of perovskite/silicon tandem solar cells are investigated by detailed balance calculations and photon management. An extended Shockley–Queisser model is used to identify fundamental loss mechanisms and link the losses to the optics of solar cells. Photon management is used to minimize losses and maximize the energy conversion efficiency. The influence of photon management on the solar cell parameters of a perovskite single-junction solar cell and a perovskite/silicon solar cell is discussed in greater details. An optimized solar cell design of a perovskite/silicon tandem solar cell is presented, which allows for the realization of solar cells with energy conversion efficiencies exceeding 32%.

The optics of microcrystalline silicon thin-film solar cells with integrated light trapping structures was investigated. Periodic grating couplers were integrated in microcrystalline silicon thin-film solar cells and the influence of the grating dimensions on the short circuit current and the quantum efficiency was investigated by the numerical simulation of Maxwell’s equations utilizing the finite difference time domain algorithm. The grating structure leads to scattering and higher order diffraction resulting in an increased absorption of the incident light in the silicon thin-film solar cell. The influence of the grating period and the grating height on the short circuit current and the quantum efficiency was investigated. Enhanced quantum efficiencies are observed for the red and infrared parts of the optical spectrum. Optimal dimensions of the grating coupler were obtained.

The perovskite material system allows for the realization of perovskite/silicon tandem solar cells with high energy conversion efficiencies at low cost. To realize such solar cells, the device geometry, the device processing, and the contact materials have to be modified in comparison to single junction perovskite solar cells. In this study, perovskite/silicon tandem solar cells are designed allowing for the generation of short-circuit current densities and energy conversion efficiencies exceeding 20 mA cm⁻² and 30%, while using realistic device structures. High short-circuit current densities can be achieved by minimizing reflection losses and optical losses of the contact layers. A hybrid approach is used to investigate the optics by combining finite-difference time-domain simulations with experimental measurements. Details on the nanophotonic design will be provided and discussed.

Light trapping and photon management of silicon thin film solar cells can be improved by a separate optimization of the front and back contact textures. A separate optimization of the front and back contact textures is investigated by optical simulations taking realistic device geometries into consideration. The optical simulations are confirmed by experimentally realized 1 μm thick microcrystalline silicon solar cells. The different front and back contact textures lead to an enhancement of the short circuit current by 1.2 mA/cm² resulting in a total short circuit current of 23.65 mA/cm² and an energy conversion efficiency of 8.35%.