CNPEM built a holder for operando X-ray imaging of whole solar cells at the Sirius synchrotron
The holder keeps a 3 × 3 mm area of a working cell stable under the X-ray beam while heat, light and bias are controlled. Vertical drift was 5 μm over a 120 °C range.
Researchers at the Brazilian Center for Research in Energy and Materials (CNPEM) in Campinas, São Paulo state, designed, built and commissioned a photovoltaic holder for the TARUMÃ end station of the CARNAÚBA X-ray nanoprobe at the SIRIUS synchrotron light source (LNLS/CNPEM). The work was published in August in Photon Science, and a news release followed on 4 November 2026. The holder allows complete solar cells to be studied with X-ray microscopy during operation acs.org
Photon Scienceacs.orgOpen source ↗.
Design and operating conditions
The holder was designed with precision-engineering principles to give nanometer-level position stability and minimal thermal drift. It controls temperature in the target area, atmosphere, illumination and bias, which makes it possible to simulate real cell operation. It supports nanoscale X-ray fluorescence, X-ray diffraction and X-ray absorption spectroscopy.
According to the release, the platform is intended mainly for perovskite cells. The cell is built on a glass chip coated on one side with indium tin oxide. The other side carries two thin platinum circuits: one is a heater, the other a temperature sensor. Heating is confined to a 3 × 3 mm area. The mount uses a titanium alloy with low thermal expansion and flexible elements that let the glass expand, and it is thermally decoupled from the sample-positioning stages.
Test results
Infrared images showed a homogeneous temperature distribution inside the 3 × 3 mm target area acs.org
Photon Scienceacs.orgOpen source ↗. Lead author Rodrigo Szostak reported a relative variation of 0.85 °C at 150 °C.
In tests at Sirius, the sample was cycled between 30 °C and 150 °C for about 20 hours. Horizontal displacement was minimal, about 1 μm according to the release. Vertical displacement reached 5 μm over the 120 °C range and was reversible on return to room temperature. At stable temperatures, the holder's position stability was better than the beam size; the beam is about 200 nm wide.
The set temperature was reached in under two minutes. At 150 °C it held with fluctuations below 0.1 °C for 50 minutes. The indium tin oxide chip can be used up to 150 °C. The authors demonstrated photovoltaic characterization together with chemical and structural mapping by several X-ray microscopy techniques. Szostak said that, as far as he knows from the literature, the holder likely offers the best positional stability achieved for this type of experiment.
