How To Quantify the Efficiency Potential of Neat Perovskite Films Perovskite Semiconductors with an Implied Efficiency Exceeding 28

Perovskite photovoltaic PV cells have demonstrated power conversion efficiencies PCE that are close to those of monocrystalline silicon cells; however, in contrast to silicon PV, perovskites are not limited by Auger recombination under 1 amp; 8208;sun illumination. Nevertheless, compared to GaAs and monocrystalline silicon PV, perovskite cells have significantly lower fill factors due to a combination of resistive and non amp; 8208;radiative recombination losses. This necessitates a deeper understanding of the underlying loss mechanisms and in particular the ideality factor of the cell. By measuring the intensity dependence of the external open amp; 8208;circuit voltage and the internal quasi amp; 8208;Fermi level splitting QFLS , the transport resistance amp; 8208;free efficiency of the complete cell as well as the efficiency potential of any neat perovskite film with or without attached transport layers are quantified. Moreover, intensity amp; 8208;dependent QFLS measurements on different perovskite compositions allows for disentangling of the impact of the interfaces and the perovskite surface on the non amp; 8208;radiative fill factor and open amp; 8208;circuit voltage loss. It is found that potassium amp; 8208;passivated triple cation perovskite films stand out by their exceptionally high implied PCEs gt; 28 , which could be achieved with ideal transport layers. Finally, strategies are presented to reduce both the ideality factor and transport losses to push the efficiency to the thermodynamic limi