Material Parameters and Perspectives for Efficiency Improvements in Perovskite Solar Cells Obtained by Analytical Modeling

K. TARETTO; M. SOLDERA; A. KOFFMAN-FRISCHKNECHT

IEEE Journal of Photovoltaics

IEEE

Año: 2017 vol. 7 p. 206 - 213

2156-3381

Current perovskite solar cells reach highefficiencies with inexpensive materials and preparation methods.But in order to understand the current values and obtain evenhigher efficiencies, the fundamental loss mechanisms ofperovskite solar cells must be elucidated and predicted byappropriate models. Here, we adapt an analytical, drift-diffusionmodel for p-i-n solar cells and obtain accurate fits to measuredcurrent voltage characteristics of planar hysteresis-freeperovskite solar cells, covering a range of illumination intensitiesand perovskite thicknesses. Our results give values of carrierrecombination liftimes above 1 µs, low effective recombinationvelocities at the interfaces between the perovskite layer and thesurrounding layers around 1000 cm/s, built-in voltages that areslightly below the open circuit voltages of around 1.05 V, andcarrier mobilities around 0.1 cm2/Vs. The obtained parametersindicate that interface and bulk recombination are competingmechanisms, none of which can be ruled out in the case of thestudied cells. Furthermore, we find that increasing the built-involtage can significantly improve efficiency in p-i-n cells, whilethe implied relatively long diffusion length encourages theinvestigation of pn?type structures as ideal perovskite solar celljunctions.