Understanding and Mitigating Interfacial Losses at the Perovskite/C60 Interface for Tandem Solar Cells

Eike Köhnen^a, Lea Zimmermann^a, Florian Scheler^a, Dorothee Menzel^a, Maxim Simmonds^a, Richard Gundermann^b, Thomas Gries^a, Edgar Edgar Nandayapa^a, Florian Matthies^a, Silvia Mariotti^a, Daniele Mantione^c, Sahil Shah^b, Hans Köbler^a, Wander Max Bernardes de Araujo^a, Julius Petrulevicius^d, Arman Mahboubi Soufiani^a, Suresh Maniyarasu^a, Tadas Malinauskas^d, Vytautas Getautis^d, Felix Lang^b, Lars Korte^a, Bernd Stannowski^a, Eva Unger^a, Antonio Abate^a, David Mecerreyes^c, Steve Albrecht^a

^aHelmholtz-Zentrum Berlin für Materialien und Energie, Solar Energy Division, 12489 Berlin, Germany

^bSoft Matter Physics and Optoelectronics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24–25, 14476 Potsdam-Golm, Germany.

^cIkerbasque, Basque Foundation for Science, Bilbao, Bizkaia, 48015, Spain.

^dDepartment of Organic Chemistry, Kaunas University of Technology, Kaunas, Lithuania

Proceedings of MATSUS Fall 2025 Conference (MATSUSFall25)

A2 Molecular Interfaces for Emerging Photovoltaics - #InterPero

València, Spain, 2025 October 20th - 24th

Organizers: Vincent M. Le Corre and Esma Ugur

Invited Speaker, Eike Köhnen, presentation 334
Publication date: 21st July 2025

Perovskite based solar cells (single- and multijunction) have emerged as highly promising candidates for next-generation photovoltaic technologies, offering low-cost fabrication, high efficiencies, and tunable bandgaps. In particular, perovskites with a bandgap of 1.68 eV are ideally suited as top cells in perovskite/silicon tandem solar cells, which gained relevance in both research and industry.

A critical challenge on the path to further efficiency improvements and industrial implementation lies at the interface between the perovskite absorber and the electron transport layer, typically C₆₀. In this talk, I will present a detailed analysis of a loss mechanism that occurs when C₆₀ is exposed to air. This degradation process not only impacts device performance but also has important implications for the design of manufacturing environments and for the accurate evaluation of interfacial engineering strategies: For example, the apparent effectiveness of an interlayer can be misinterpreted if C₆₀ degradation is not properly accounted for.

Furthermore, I will demonstrate two approaches to reduce interfacial losses:
(1) The incorporation of functional interlayers between perovskite and C₆₀, reduce non-radiative recombination by passivation and improved bandalignment.
(2) The use of an evaporable industrially relevant alternative to C₆₀ that shows reduced interfacial losses.

The results presented are relevant for both p-i-n single-junction and perovskite-based multi-junction solar cells and offer concrete strategies for improving device architectures and manufacturing processes-paving the way for stable, scalable, and high-efficiency perovskite photovoltaic technologies.

nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.

MATSUS

Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.

International Conference on Hybrid and Organic Photovoltaics

International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics

The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.