Publication date: 22nd July 2026
Optimizing organic photovoltaic (OPV) devices requires an accurate, multiscale understanding of exciton transport. However, modeling these processes from first principles introduces severe computational difficulties. In this presentation, I will outline our on-going efforts to overcome these difficulties by combining density functional theory, ab initio structure prediction, and machine learning models.
We first discuss our efforts to model the surface of the coordination polymer copper thiocyanate (CuSCN), a wide-bandgap semiconductor often used as a hole-transporting layer in OPV devices. Finite slab models of CuSCN surfaces often suffer from artificial dipole moments, causing unphysical band energy drifts and bandgap closure (Figure). We introduce a novel passivation scheme utilizing "pseudohydrogen" atoms via the virtual crystal approximation (VCA) to counteract internal electric fields. While this VCA approach restores the bandgap, it induces an incorrect n-type behavior. By performing a comprehensive ab initio structure search, we demonstrate that surface reconstructions of CuSCN(001) offer a self-passivation mechanism that minimizes surface energy, reduces internal fields, and correctly reproduces experimental p-type semiconducting behavior. These results strongly support the use of reconstructed CuSCN surface slabs when modeling CuSCN-based OPV devices.
We then discuss efforts to simulate exciton transport organic semiconductors, where calculating intermolecular couplings and other exciton transport parameters from first principles is excessively cost-prohibitive. We present a graph neural network (GNN) architecture that dramatically accelerates prediction times without sacrificing the accuracy needed for exciton transport simulations. Importantly, our GNN generalized across diverse molecular systems by utilizing atomic transition charges as an intermediate representation. This GNN successfully predicts exciton couplings for a broad class of fused-ring electron acceptors, enabling robust exciton diffusion simulations without repeated quantum chemical calculations [1], [2], [3].
Kyoto University On-Site Laboratory Initiative; JSPS Bilateral Program/NZ Catalyst Grant for Joint Research Projects (Grant Nos. JPJSBP120231003 and 22-VUW-014-JSP); JSPS Postdoctoral Fellowship; East Asia Science and Innovation Area Joint Research Program (e-ASIA JRP Grant No. JPMJSC24E3, RSCHTRUSTVIC2449).
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.
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.
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.