TY  - GEN
A1  - Stolterfoht, Martin
A1  - Grischek, Max
A1  - Caprioglio, Pietro
A1  - Wolff, Christian Michael
A1  - Gutierrez-Partida, Emilio
A1  - Peña-Camargo, Francisco
A1  - Rothhardt, Daniel
A1  - Zhang, Shanshan
A1  - Raoufi, Meysam
A1  - Wolansky, Jakob
A1  - Abdi-Jalebi, Mojtaba
A1  - Stranks, Samuel D.
A1  - Albrecht, Steve
A1  - Kirchartz, Thomas
A1  - Neher, Dieter
T1  - How to quantify the efficiency potential of neat perovskite films
BT  - Perovskite semiconductors with an implied efficiency exceeding 28%
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - 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-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-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-circuit voltage and the internal quasi-Fermi level splitting (QFLS), the transport resistance-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-dependent QFLS measurements on different perovskite compositions allows for disentangling of the impact of the interfaces and the perovskite surface on the non-radiative fill factor and open-circuit voltage loss. It is found that potassium-passivated triple cation perovskite films stand out by their exceptionally high implied PCEs > 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 limit.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1434 
KW  - non-radiative interface recombination
KW  - perovskite solar cells
KW  - photoluminescence
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-516622
SN  - 1866-8372
IS  - 17
ER  - 
TY  - GEN
A1  - Caprioglio, Pietro
A1  - Stolterfoht, Martin
A1  - Wolff, Christian Michael
A1  - Unold, Thomas
A1  - Rech, Bernd
A1  - Albrecht, Steve
A1  - Neher, Dieter
T1  - On the relation between the open‐circuit voltage and quasi‐Fermi level splitting in efficient perovskite solar cells
T2  - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe
N2  - Today's perovskite solar cells (PSCs) are limited mainly by their open‐circuit voltage (VOC) due to nonradiative recombination. Therefore, a comprehensive understanding of the relevant recombination pathways is needed. Here, intensity‐dependent measurements of the quasi‐Fermi level splitting (QFLS) and of the VOC on the very same devices, including pin‐type PSCs with efficiencies above 20%, are performed. It is found that the QFLS in the perovskite lies significantly below its radiative limit for all intensities but also that the VOC is generally lower than the QFLS, violating one main assumption of the Shockley‐Queisser theory. This has far‐reaching implications for the applicability of some well‐established techniques, which use the VOC as a measure of the carrier densities in the absorber. By performing drift‐diffusion simulations, the intensity dependence of the QFLS, the QFLS‐VOC offset and the ideality factor are consistently explained by trap‐assisted recombination and energetic misalignment at the interfaces. Additionally, it is found that the saturation of the VOC at high intensities is caused by insufficient contact selectivity while heating effects are of minor importance. It is concluded that the analysis of the VOC does not provide reliable conclusions of the recombination pathways and that the knowledge of the QFLS‐VOC relation is of great importance.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 774 
KW  - electro‐optical materials
KW  - perovskite solar cells
KW  - photovoltaic devices
KW  - thin films
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-437595
SN  - 1866-8372
IS  - 774
ER  -