The environmental testing system, developed by the UK’s National Physical Laboratory (NPL), comprises portable environmental chambers with built-in electrical connections coupled to an environmental control system that generates, maintains and logs precise environments for the duration of the tests. Measurements can be performed with independent control of oxygen and humidity concentrations with up to part-per-million precision.
The environmental testing system was designed to test the intrinsic stability of highly sensitive electronic and optical components, such as those used in plastic and thin-film devices. Typically such components require encapsulation for protection from the environment. Product lifetime is a function of the quality of the encapsulation and the stability of the components under the low concentrations of contamination that they will experience during production and operation.
Hence, the environmental testing system simulates such conditions in order to accelerate lifetime testing of components under precisely controlled environments. Designed to enable various methods of in-situ characterisation the system facilitates failure-mode identification.
- Highly controlled and automated accelerated lifetime testing of sensitive components while maintaining realistic degradation processes
- Materials and process screening for improving component/stack/product stability
- Transportation of devices and films between characterisation equipment under constant atmosphere
- Identifying causes of device failure
- Simulation of conditions within encapsulation
- Measure reversible and irreversible response to chemical stimulus such as oxygen doping, organic semiconductors, perovskites, metal oxides, graphene, nanowires, photovoltaics, thin-film transistors, light-emitting devices, sensors, etc.
Portable environment chambers
Samples are contained in specially designed leak-tested environment chambers. The chambers are designed to maintain long-term environmental stability while offering easy optical and electrical access to samples. Downtime between tests is kept to a minimum as exchange of like-for-like samples takes just a few minutes inside a glove box.
- The chambers’ portability enables samples to be loaded in an inert environment and to be transported between instruments without changing the atmosphere.
- Enables fast, repeated electrical connections to user-defined contact configurations
- Optical access through highly transmissive broadband windows allows in-situ characterisation by a range of spectroscopic and microscopic imaging techniques as well as light soaking and functional characterisation of PV and light-emitting devices.
- Use of low-outgassing, chemically inert materials facilitates environment control and resistance to chemicals and solvents
- Leak rates as low as 1 ppm oxygen per hour maintain a stable atmosphere even when disconnected from the environmental control system.
Environmental control system
Figure 1 Environmental control software data logging page.
Chambers can be connected to a gas supply and monitoring system to ensure a stable and precisely-controlled environment. The system allows the users to vary the concentrations of oxygen and water vapour in the chambers, from part-per-million to ambient conditions. Control of other gases, such as solvents, is also possible. The supplied software enables fully automated control and continuous logging of the chamber environment with a simple user interface.