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This brief treats two problems usually handled separately in solution-processed perovskite films, residual DMSO removal and defect sealing, as one manufacturing variable: coordination state. It outlines a process that controls both with two wavelengths applied in sequence, together with a validation design. The full report is available in Korean. An English summary is provided on this page.
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Summary
In solution-processed perovskites, removing residual DMSO and passivating defects have been treated as separate problems. When the coordination state, whether a molecule is bound to Pb, becomes a manufacturing variable, the two become consecutive operations on the same Pb site. The first wavelength, 9.85 μm, is aligned with the S=O stretch of Pb-coordinated DMSO (about 1013 cm⁻¹) and breaks only that coordination bond to vacate the site. The second, 5.78 μm, activates the free carbonyl of PMMA (about 1730 cm⁻¹) and seats it on undercoordinated Pb that did not return to the lattice. The two wavelengths are switched on in sequence, and once a carbonyl is seated its absorption peak shifts to 1721 cm⁻¹, so its activation stops by itself. The quantitative values are predictions based on resonant-absorption and heat-transfer simulation, and a device-level validation design is included.
Conclusion
Temperature, concentration and time have long been the control variables of perovskite solution processing. This brief adds the coordination state, whether a molecule is bound to Pb. Because coordination state shows up in the wavenumber of the oxygen stretching vibration, tuning the irradiation wavelength to that wavenumber drives only a chosen state. On this variable, residual DMSO removal and defect passivation become two consecutive operations on the same Pb site. At the inlet, the first wavelength of 9.85 μm concentrates energy in the S=O stretch of Pb-coordinated DMSO (about 1013 cm⁻¹) and breaks the coordination bond before the lattice decomposes, vacating the site. In a simulated preliminary trend, the condition aligned with the coordination peak left the least S=O, while unselective continuous 10.6 μm irradiation left much of it even when the surface reached 138 °C. At the outlet, the second wavelength of 5.78 μm activates the free carbonyl of PMMA supplied at low coverage (about 1730 cm⁻¹), which binds first to undercoordinated Pb because of its higher affinity for oxygen donors. Coordinated S=O (1013 cm⁻¹), free C=O (1730 cm⁻¹) and coordinated C=O after seating (1721 cm⁻¹) are separated on the wavenumber axis, so the two wavelengths can be driven independently. They are never on at the same time; the second starts only after the loss of coordinated DMSO is confirmed. A seated carbonyl stops its own activation as its peak shifts, and because carbonyls seat only at defects, the regular lattice surface stays open for hole transport. Pulses are designed to keep the average temperature below the 100 °C onset of organic decomposition, and simulation predicts a time-averaged temperature of 42 °C. All quantitative values are predictions based on resonant-absorption and heat-transfer simulation. As the next step, the brief proposes reading FTIR/ATR, XPS, GIWAXS, PL/TRPL and device characteristics on one device set, and six control groups, from a baseline to off-resonance irradiation, to test whether wavelength alignment dominates and whether sequential operation is necessary. Patent applications have been filed for both the inlet and outlet processes.
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- Solar
