Molecules that self-assemble into monolayers for efficient perovskite solar cells

The molecule organises itself on the electrode surface until a dense, uniform monolayer is formed.

The molecule organises itself on the electrode surface until a dense, uniform monolayer is formed. © Saule Magomedoviene / HZB

“Self‐Assembled Hole Transporting Monolayer for Highly Efficient Perovskite Solar Cells”. Cover of current issue of Advanced Energy Materials.

“Self‐Assembled Hole Transporting Monolayer for Highly Efficient Perovskite Solar Cells”. Cover of current issue of Advanced Energy Materials. © Wiley/VCH

A team at the HZB has discovered a new method for producing efficient contact layers in perovskite solar cells. It is based on molecules that organise themselves into a monolayer. The study was published in Advanced Energy Materials and appeared on the front cover of the journal.

In recent years, solar cells based on metal halide perovskites have achieved an exceptional increase in efficiency. These materials promise cost-effective and flexible solar cells, and can be combined with conventional PV materials such as silicon to form particularly efficient tandem solar cells. An important step towards mass production is the development of efficient electrical contact layers that would allow deposition of perovskite layers on various substrates.

Molecules form monolayer

Now the HZB Young Investigator Group headed by physicist Dr. Steve Albrecht, in collaboration with former DAAD exchange student Artiom Magomedov from Kaunas University of Technology (KTU) in Lithuania, has synthesized a novel molecule that self-assembles into a monolayer (SAM). The team successfully used this new material as a hole-conducting layer in perovskite solar cells. The molecule is carbazole-based and bonds to the oxide of the transparent electrode via a phosphonic acid anchoring group. Due to the anchoring fragment, this molecule organises itself on the electrode surface until a dense, uniform monolayer is formed. The ultra-thin layer exhibits no optical losses and, thanks to its self-organising property, could conformally cover any surface – including textured silicon in tandem solar-cell architectures.

Adaption possible

Extremely low material consumption is achieved with this technique, and the chemical structure of the SAMs can be adapted to the desired application. Thus, SAMs could also serve as a model system for future investigations of the properties of perovskite interfaces and growth.

New generation to be developed at HySPRINT Lab

The work took place at the HySPRINT laboratory of the HZB where Albrecht's group is now conducting research on a new generation of self-assembling molecules, which already enable solar cells with efficiencies of over 21 %.

Patent application filed

Since this approach to perovskite solar cells has never been considered before and can potentially play a role in industrial processes, the HZB and KTU teams have filed a patent application on the molecule and its use. As the scientific interest for this new contact material class is enormous, the journal has displayed an illustration from the paper on the front cover of the current issue.

Published in Advanced Energy Materials 2018: “Self‐Assembled Hole Transporting Monolayer for Highly Efficient Perovskite Solar Cells”. Artiom Magomedov, Amran Al‐Ashouri, Ernestas Kasparavičius, Simona Strazdaite, Gediminas Niaura, Marko Jošt, Tadas Malinauskas, Steve Albrecht and Vytautas Getautis.

Doi: 10.1002/aenm.201870139

Autor: Amran Al Ashouri, PhD student and shared first author of the publication

You might also be interested in

  • Rhombohedral graphite as a model for quantum magnetism
    Science Highlight
    27.09.2022
    Rhombohedral graphite as a model for quantum magnetism
    Graphene is an extremely exciting material. Now a graphene variant shows another talent: rhombohedral graphite made of several layers slightly offset from each other could enlighten the hidden physics in quantum magnets.
  • 8th World Conference on PV Energy Conversion
    News
    19.09.2022
    8th World Conference on PV Energy Conversion
    The WCPEC-8 woll take place from 26 – 30 September 2022 in the Milano Convention Centre in Milan, Italy.
    Also scientists from PVcomB will present latest results about their research work to photovoltaics.

  • 40 years of research with synchrotron light in Berlin
    News
    14.09.2022
    40 years of research with synchrotron light in Berlin
    Press release _ Berlin, 14 September: For decades, science in Berlin has been an important driver of innovation and progress. Creative, talented people from all over the world come together here and develop new ideas from which we all benefit as a society. Many discoveries – from fundamental insights to marketable products – are made by doing research with synchrotron light. Researchers have had access to this intense light in Berlin for 40 years. It inspires many scientific disciplines and is an advantage for Germany.