Integrated Offline Defect Inspection System for Perovskite Photovoltaics

The Integrated Offline Defect Inspection System for Perovskite Photovoltaics is designed for materials research, device performance evaluation, and failure analysis. Integrating photoluminescence (PL), electroluminescence (EL), and bright- and dark-field automated optical inspection (AOI), the offline system accommodates perovskite and perovskite/silicon tandem cells of various sizes and enables multiscale inspection, from large-area imaging to localized microscopic defect observation. Optional capabilities include high-resolution imaging, PL spectroscopy, time-resolved photoluminescence (TRPL), and photocurrent/photovoltage mapping. Combined with PL quantum yield (PLQY), quasi-Fermi level splitting (QFLS), and pseudo-J–V imaging, these capabilities characterize the spatial distribution of optoelectronic properties in materials and devices. AI-assisted defect identification, classification, statistical analysis, and uniformity assessment help correlate defect characteristics with performance variations, providing experimental insights for materials screening, process optimization, and improvements in efficiency and stability.

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Features

PL, EL & AOI Inspection

Multiple Sample Sizes & Tandem Cell Compatibility

High-Resolution Imaging: ~5 μm

Application Examples

① Routine Imaging Inspection

Sample: a 30 cm × 30 cm photovoltaic panel with a conventional perovskite composition. Images from left to right: AOI (bright-field and dark-field), PL, and EL. Scale bars: 2 cm.

② Integrated Measurement Modules

The system can integrate high-resolution imaging, spectroscopy, and scanning photovoltage/photocurrent modules.

Figure key: upper left, in situ high-resolution PL image; lower left, in situ high-resolution bright-field image; center, standard-resolution PL image of a 10 cm × 10 cm sample; upper right, photocurrent/photovoltage scanning image; middle right, spectroscopy; lower right, time-resolved photoluminescence (TRPL) measurement.

③ Module Functions and Spectral Imaging

In situ high-resolution measurements: AOI, PL, and EL measurements at higher spatial resolution. The field of view and spatial resolution can be customized to characterize defects and scribe lines, and to inspect small samples.

Photocurrent/photovoltage module: measures short-circuit current and open-circuit voltage in different sample regions to identify local variations in electrical response.

Time-resolved photoluminescence (TRPL): measures carrier lifetime in perovskite materials to reveal carrier recombination and charge-extraction dynamics.

Spectroscopy: measures PL and EL spectra at different sample locations to reveal the spatial distribution and variation of perovskite composition; spectral scanning imaging is also supported.

Bottom images, left to right: integrated PL spectral intensity map; PL spectral center-wavelength map; PL spectral full width at half maximum (FWHM) map.

④ AI-Based Automated Defect Identification

Automated defect identification using AI and large datasets. Sample size: 5 cm × 10 cm.

Panels from left to right: PL image; PL defect identification; PL mapping with defect classification and counts; PL image grayscale histogram for the sample region.

Defect classes and counts: light defect, 12; light defect with dark ring, 1; dark defect with dark ring, 3; dark defect with light ring, 46; dark defect, 252; film defect, 3. Mean grayscale value: 68.9. Grayscale variance: 14.8.

⑤ Additional Defect Classification Results

Sample size: 5 cm × 10 cm. The two left-hand panels are labeled “PL image” and “PL defect identification” in the source. The charts are labeled “EL mapping with defect classification and counts” and “EL image grayscale histogram for the sample region.”

Defect classes and counts: light defect, 213; light defect with dark ring, 7; dark defect with dark ring, 4; dark defect with light ring, 86; dark defect, 89; film defect, 4. Mean grayscale value: 72.0. Grayscale variance: 38.8.

PL, EL and AOI Imaging
Field of View	35 cm × 35 cm
Spatial Resolution	Approximately 50 μm/pixel
PL Excitation Sources	532 nm LED area light source (other wavelengths optional); 850 nm LED area light source for tandem solar cells
Illumination Uniformity	>90%
Illumination Intensity Range	0.01–1.2 sun
Image Acquisition Time	Typically <1 s, depending on the PL and EL signal intensity of the sample
High Resolution Imaging
Field of View	2.5 cm × 2.5 cm
Spatial Resolution	Approximately 5 μm/pixel (higher resolution available on request)
PL Spectroscopy
Excitation Source	532 nm laser (an additional 850 nm source is available for tandem solar cells)
Spectral Acquisition Range	350–1000 nm (a customized near-infrared spectrometer is available for tandem solar cells)
Spectral Resolution	Wavelength resolution: 0.25 nm; optical resolution: 1.8 nm
Additional Capabilities
Electrical Characterization	Scanning photocurrent and photovoltage imaging
AI Analysis	AI-based defect identification
Advanced Imaging	Imaging of photoluminescence quantum yield (PLQY), quasi-Fermi level splitting (QFLS), and pseudo-J–V characteristics