Disorder induced Voc losses and dimerization related Jsc losses: The critical role of morphology during burn-in

Markus Biele^a, Christoph Brabec^a, Thomas Heumueller^a^,^b, Timothy Burke^b, Michael McGehee^b, William Mateker^b, Andreas Distler^c, Hans-Joachim Egelhaaf^c

^aUniversity of Erlangen-Nuremberg, Martensstraße, 7, Erlangen, Germany

^bStanford University, Stanford, CA 94305, United States

^cBelectric GmbH, Nürnberg, 90443, Germany

International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics 2015 (HOPV15)

Roma, Italy, 2015 May 11th - 13th

Organizer: Filippo De Angelis

Oral, Thomas Heumueller, presentation 156
Publication date: 5th February 2015

We have studied the degradation of a variety of organic photovoltaic (OPV) materials and observe an increase of energetic disorder in all investigated materials using charge extraction and photocurrent spectroscopy. This increased energetic disorder lowers the open-circuit voltage in amorphous materials by broadening the density of states. Both, the temperature and light intensity dependence of those disorder induced Voc losses can be described with an analytical model using only one fit parameter. No significant change of the recombination rate is observed after degradation. Crystalline materials also show an increase of energetic disorder, but no significant losses in open-circuit voltage. We show that the carrier densities at open-circuit voltage are several times higher in crystalline materials than in amorphous materials. For the large carrier density in crystalline materials, an increase of energetic disorder has a relatively smaller effect than in amorphous materials where the steady state carrier concentration is much lower. Fullerene dimerization has been observed to cause short circuit current losses in organic solar cells made with certain materials. We investigate under which conditions dimerization occurs and show the importance of morphology and excited species on the reaction mechanism. Simply changing the operating conditions of the investigated solar cell from Voc to Jsc significantly reduces the amount of dimerization related performance losses. Finally, as the third essential device parameter, we investigate fill factor losses in organic solar cells. By de-laminating and replacing electrodes after degradation, we can show that in many cases fill factor losses are related to interface defects.
Increased energetic disorder after burn-in causes Voc losses in amorphous materials but not in crystalline materials that have a high charge carrier density.

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.