Solar cells based on lead halide perovskites have recently emerged showing a tremendous increase of power-conversion efficiency which exceeded 22%. In this tutorial talk, the device physics of perovskite solar cells is addressed. The focus is on recombination of charge carriers because this process is ultimately limiting the performance.
The origin of the open-circuit voltage is discussed based on the reciprocity relation between electroluminescence and photovoltaic quantum efficiency.1,2 Sharp absorption onset and high radiative recombination yield due to an extraordinary defect tolerance are identified as reasons for the outstanding optoelectronic properties of perovskites. Furthermore, the role of defect and surface recombination are addressed.
Surprisingly, a current-voltage measurement of perovskite solar cells yields different results dependent on the initial voltage of the sweep. The resulting hysteresis in the current-voltage curve is related to recombination as well.3 These results are explained based on the mixed ionic and electronic conductivity of the material, where displaced ions change interface and defect recombination. Reversible photo-induced and irreversible heat-triggered degradation mechanisms on the timescale of minutes to hours are covered as well.
An outlook is given on strategies aiming for a further improvement of open-circuit voltage and performance of perovskite solar cells toward their thermodynamic limit.
Auditorium between Building 4 and 5
15:30 - 16:30