This is a sponsored post by KYOCERA Document Solutions Inc.
Kyocera Document Solutions is conducting joint research with Professor Takeshi Sano, Deputy Director of Yamagata University’s Organic Innovation Center for Organic Electronics (INOEL), and his team to develop materials aimed at addressing the challenges associated with PTAA a widely used material in inverted PSCs. In parallel, the team has also begun developing a new self-assembled monolayer (SAM) material.
Kyocera Document Solutions and the Innovation Center for Organic Electronics at Yamagata University
Currently, Kyocera and the researchers at INOEL are focusing on developing new hole transport materials for inverted structures, specifically a new polymer to replace PTAA and novel self-assembled monolayer materials.
Vacuum deposition, evaporation and sublimation equipment at Kyocera Document Solutions and Yamagata University
The results of the first phase of the collaboration were presented at the 86th JSAP Autumn Meeting 2025. The presentation title was “Evaluation of inverted perovskite solar cells using PTAA-based hole-transporting polymers.”
PTAA has been widely used as a hole transport layer in perovskite solar cells due to its structural versatility and excellent solution processability. However, when used in inverted PSCs that require a perovskite layer to be stacked on top of a hole transport layer, the low surface energy of PTAA results in insufficient wetting of the thin film when the PTAA film comes into contact with the perovskite precursor solution during manufacturing, thereby degrading the interfacial quality of the solar cell.
In the worst case, it may even be impossible to form a uniform perovskite layer.
In this study, the team successfully improved the wettability of PTAA without compromising the characteristics of perovskite solar cells by enhancing PTAA’s hydrophilicity and achieving an optimal HOMO level.
The newly developed inverted perovskite solar cell using the new HTM achieved conversion efficiencies equal to or higher than those of PTAA-based devices.
Simultaneously, the team confirmed that the contact angle of the perovskite precursor solution on the HTM was reduced, improving wettability during perovskite film deposition
Jsc, Voc, FF and efficiency of the Wige-band gap inverted PSCs used PTAA and New HTM
Contact Angle of PTAA and New HTM in DMF/DMSO Mixed Solvent
Perovskite device appearance and structure
However, even with the newly developed polymer-based HTM, wettability with perovskite precursor solutions remains insufficient compared with NiOx and PEDOT:PSS.
Furthermore, for mass production of inverted perovskite solar cells, uniform coating performance that prevents beading over large areas is required.
The company continues to collaborate with Yamagata University to advance research and development of new polymer-based HTMs with further improved wettability.
About Yamagata University
Prof. Takeshi Sano, who is conducting research in collaboration with the company, is affiliated with INOEL at Yamagata University, where he serves as Deputy Director and Professor at INOEL.
His research areas include organic electronic devices, thin films, optoelectronics and electroluminescence, with an emphasis on the development of organic photovoltaic cells (OPVs) and perovskite solar cells (PSCs). His work comprises semi-transparent OPV panels designed for window applications, as well as foundational technology for high-efficiency, low-temperature-processed PSCs.
Yamagata University has expertise in device design and evaluation technologies for PSCs, especially those featuring inverted device structures for both single-junction and tandem cells.
Meanwhile, Kyocera Document Solutions has advanced synthesis technology for triarylamine compounds used as hole-transport materials and maintains a compound database.
They believe that collaboration between Yamagata University and the company can drive innovation in perovskite solar cells.
About Kyocera Document Solutions
Kyocera Document Solutions operates globally within the Kyocera Group, offering a wide range of products and services including printers, multifunctional products (MFPs), commercial and industrial inkjet printers, and total document solutions. In addition to equipment manufacturing, Kyocera Document Solutions also develops and produces OPCs in-house—a core component of its devices.
Since the 1990s, Kyocera Document Solutions has independently developed high-performance HTMs to support the advanced functionality of OPCs. Drawing on its experience with organic low-molecular-weight compounds and polymers, such as aromatic tertiary amines used in OPCs, the company has applied optimal manufacturing techniques to produce Spiro-OMeTAD and PTAA with high quality and stability. These materials are now available in kilogram-scale quantities.
These compounds have successfully completed pilot production at the kilogram scale and are now available for stable, cost-effective supply.
Toward Mass Production and Sustainability
Preparations for mass production of HTMs for perovskite solar cells have been completed. Stable-quality prototypes are available upon request, and custom development tailored to specific customer needs is offered. Through continued innovation in materials, the company supports the widespread use of perovskite solar cells around the world and contributes to the realization of a sustainable society.
Learn more here
This was a sponsored post by KYOCERA Document Solutions Inc.