☀ Solar cell materials

Green energy, Photovoltaic Solar Cell with hand

Halide perovskite and buckyballs: Route to efficient and stable solar cell materials


Solar energy plays an increasingly important role in the overall energy production.

Market data shows that by 2020 several countries led by Germany, Italy, Spain, Greece, UK, Australia were getting over 5%, sometimes close to 10% of their energy from solar power.

This progress is of course linked to materials research – it is imperative to have photovoltaic materials that are efficient in converting solar energy to electricity.

Conversion efficiency improved from 2-3% to 20-25%, and, in some cases, 40%, over the last years.

There is still a lot to be done to produce even more efficient converters.

BIOVIA’s Riichi Kuwahara is one of the authors of the recent paper “Photo-energy conversion efficiency of CH3NH3PbI3/C60 heterojunction perovskite solar cells from first-principles” in Materials Advances.

This work used BIOVIA Materials Studio DMol3 solver to look into conversion efficiency of the interface between a halide perovskite, MAPbI3, and a C60 buckyball.

The study showed that under certain alignment conditions an efficiency of 19% can be achieved. A more fundamental result of this study is a better understanding of the role of dipoles in the perovskite structure for electron transfer across the interface. This investigation gives a solid basis to future work on applications of ferroelectrics and electrical poling to improve efficiency of halide perovskite solar cells.

Schematic illustration
Figure 1. Schematic illustration of the energy-level diagram for the MAPbI3 and C60 in the hybrid perovskite/fullerene heterojunction. Eg is the energy gap of MAPbI3 and E is the dissociation energy of the electron-hole pairs. The three-fold degenerate LUMO of C60 fullerene has three energy level from LUMO to LUMO+2.


Further research showed that buckyballs not only improve conversion efficiency, but can be used reduce degradation and improve air stability. BIOVIA’s Riichi Kuwahara was part of the group of authors of “Electronic structure of Li+@C60 adsorbed on methyl-ammonium lead iodide perovskite CH3NH3PbI3 surfaces” paper in Materials Advances, the work that helps to understand one particular mechanism for MAPbI3 perovskite stabilization.

This study looks at doping of surfaces with Li+@C60 complexes to suppress surface oxidation of MAPbI3 perovskite.

The work was done with Materials Studio DMol3 and showed why the modified material is a good hole conductor – better than just Li-doped perovskite.

An energetically isolated hole level localized in the Li@C60 complex helps to suppress surface oxidation and makes material more stable on air. This conclusion is valid for any adsorption geometry on the MAPbI3 perovskite surface, making buckyballs a reliable stabilizer for this solar cell material.


Victor Milman

BIOVIA, Dassault Systèmes
Senior Director of the Quantum Mechanics and Nanotechnology R&D Team, Victor Milman, Ph.D., joined BIOVIA in 1994 and currently serves as a senior fellow and manager of quantum mechanics and nanotechnology research and development team. He graduated from Moscow Institute of Physics and Technology and received his doctorate in solid state physics from The Ukrainian Academy of Sciences. His subsequent research at the Institute of Metal Physics in Kiev focused on development of first principles techniques for study of lattice properties of inorganic crystals. This work continued at the Cavendish Laboratory, Cambridge, where he was employed as a Research Associate for the SERC Collaborative Computational Project in electronic structure of solids. This activity in the group of Professor Heine and Professor Payne culminated in the public release of CASTEP, a revolutionary code for quantum-mechanical modelling of solids and surfaces. Milman further worked for a year as a visiting research fellow at the DOE Oak Ridge National Laboratory, concentrating on applications of CASTEP to physics of semiconductors, from modelling growth processes to study of extended defects. Victor Milman has 150 peer-reviewed publications with the h-index of 29, which reflects both productivity and high scientific impact of his research. His contributions include numerous conference presentations, co-supervision of doctorate students with University of Cambridge and with University College London, organization of meetings and symposia, regular refereeing of papers for the major journals in physics and chemistry.

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