Title
On the Relation between the Open-Circuit Voltage and Quasi-Fermi Level Splitting in Efficient Perovskite Solar Cells
Date Issued
01 September 2019
Access level
open access
Resource Type
journal article
Author(s)
Caprioglio P.
Stolterfoht M.
Wolff C.M.
Unold T.
Albrecht S.
Neher D.
Institute for Silicon Photovoltaics
Publisher(s)
Wiley-VCH Verlag
Abstract
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.
Volume
9
Issue
33
Number
1901631
Language
English
OCDE Knowledge area
Ingeniería de materiales
Scopus EID
2-s2.0-85071831326
Source
Advanced Energy Materials
ISSN of the container
16146832
Sponsor(s)
S.A. acknowledges funding from the German Federal Ministry of Education and Research (BMBF), within the project “Materialforschung für die Energiewende” (grant no. 03SF0540), and the German Federal Ministry for Economic Affairs and Energy (BMWi) through the “PersiST” project (grant no. 0324037C). Additional funding came from HyPerCells (a Joint Graduate School of the Potsdam University and the HZB) and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 182087777 – SFB 951. Universität Potsdam - UP
Sources of information: Directorio de Producción Científica Scopus