TNO is an independent Dutch organization for applied scientific research with a strong focus on achieving a more sustainable society. TNO and the Belgian research institute imec together lead Solliance solar research, a public-private partnership of companies, R&D institutes and universities from the Netherlands, Belgium and Germany working in thin film photovoltaic solar energy. In order to strengthen the region’s position as a world player in PV, Solliance is creating the required synergy by consolidating and coordinating the activities of 250 researchers in industry, at research institutes and universities.

Various state-of-the-art laboratories and pilot production lines are jointly used for dedicated research programs which are executed in close cooperation with the solar business community. The three research programs that have been setup at Solliance each have their own road map and share the common vision:

  • Perovskite based Solar Cells:  the research focuses on the development of perovskite solar cells and in particular on life span, efficiency and the scalability of the production technology. The research often has a fundamental character.
  • Innovative Module Technology:  for low cost / high performance and new applications, e.g. material reduction in absorber, fully adaptable monolithic interconnection on flexible substrates and a cost-effective barrier and protective layer.
  • Application Integration Technology: aimed at aesthetic application of thin-film modules in building materials, infrastructure and vehicles. This by developing technology for semi-finished products and come to dedicated solar foils that can be seamlessly integrated in existing production methods.

Solliance offers participation in its research programs and opens up its lab facilities to new entrants, either from industry or in research. On the basis of clear Intellectual Property (IP) agreements, each industrial partner can participate in this research effort, or alternatively, hire equipment and experts to further develop its own technology.

Within the Innovative Module Technology research program at Solliance much experience has been gained over the past decade regarding reliability research on TF-PV. Setups for standard dark damp heat (DH, at 85C and 85% relative humidity) and DH under 1 sun illumination with possible electrical loads are available in the laboratories of the Solliance headquarters in Eindhoven.


The main goal of Solliance within the PEARL TF-PV project is to obtain a better understanding of the origin of defects observable in thin film modules with electroluminescence (EL) and to determine the impact of these defects on device performance, expected lifetime and degradation behavior. This knowledge should facilitate the interpretation of EL images obtained in the field from installed modules.

The more specific sub-goals of Solliance within the project are:

  • To obtain reproducible electroluminescence (EL) images of defects in a large number of laboratory scale cells and minimodules (devices)
  • To determine the origin of the observed defects on a fundamental/material level by combining different measurement techniques
  • To subject a large number of devices to accelerated lifetime tests (ALT’s) and follow defects over the course of degradation
  • To classify identified defects based on their origin, appearance in EL, behavior under degradation and impact on device performance, degradation and lifetime.
  • To add the obtained EL images to the defect catalogue/database constructed over the course of the PEARL TF-PV project.

During the PEARL TF-PV project a large number of laboratory scale devices with different types of defects are exposed to DH and monitored using EL in and various other measurement techniques. This allows obtaining a better insight into the possible origins of different defects observable in CIGS-based devices with EL, their impact on device performance, their development over the course of the lifetime of the device, and their impact on the expected lifetime of the devices. With this knowledge it should become easier to interpret EL images obtained on commercial modules in the field on severity and potential future failure. 


Mirjam Theelen,


Figure 1: Description of activities at Solliance within PEARL: initial characterization of samples, degradation in climate chamber with variable stresses and monitoring during degradation.
Figure 2: Comparison of the images obtained of the active area of a laboratory sample with architecture as shown in Figure 3 in photoluminescence (PL), electroluminescence (EL), illuminated lock-in thermography (ILIT) and dark lock-in thermography (DLIT). The image obtained of the hotspot observed in ILIT and DLIT with scanning electron microscopy (SEM) is also shown.