Ageing of an electrochromic device, especially of the electrolytic layer

• Applicant: Professor Dr.-Ing. Hans-Peter Heim
• Subject Area: Plastics Engineering
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 397477553

In this research project the ageing behaviour of chromogenic systems basing on polymers shall be investigated. Chromogenic systems (CS) are materials or multilayer systems able to change their colour or transparency by an outer stimulus, like light, voltage, temperature or pressure. A special group of CS are electrochromic devices (ECD), changing their optical properties when voltage is applied. Potential applications can be found everywhere, where panes or displays shall be actively switched. Only few systems are in use at present. All systems that are currently known from application or literature show weaknesses concerning their ageing behaviour.The design of the so-called battery type consists of two polymer substrate halves, both with an electrode layer and an additional counter or working electrode. These sheets are bonded by an ionic conducting, but electrically insulating electrolyte. In this case an appropriate modified PU functions as the electrolyte and laminates the two substrate halves. Compared to liquid or gel-like electrolytes, the curing PU system is advantageous regarding thermal resistance and dimensional stability during further processing like back-injection moulding or thermoforming, as shown in preliminary work of the applicant. Additionally, first investigations showed a much better ageing resistance, also due to fewer interactions with the other layers of the ECD. Because of this, in this project the ageing of this especially for plastic processing suitable ECD type shall be investigated. The research work includes extensive experimental activity, which will be analysed and rendered tangible by means of description with statistic models.

• DFG Programme: Research Grants