Step 1. Excitation Light Source Setup

Step 1. Excitation Light Source Setup (Using 405 nm laser as an example):

The excitation light source is coupled to the integrating sphere via fiber optic coupling.

Figure 1: The left image shows a 405 nm laser source with fiber coupling accessories, allowing excitation light to be transmitted through the optical fiber. The right image shows the integrating sphere used for Photoluminescence Quantum Yield (PLQY) measurements, with optical modules mounted on the side for fiber connection and excitation light input.

Step 2. Sample and Reference Preparation

Step 2. Sample and Reference Preparation:

Prepare the test sample for Photoluminescence Quantum Yield (PLQY) measurement and a blank reference. For example, when measuring a thin film sample, the blank reference would be an uncoated glass substrate.

Figure 2: The right image shows the Sample for PLQY measurement (thin film sample), while the left image shows the Blank reference (uncoated glass substrate).

Step 3. Sample Loading into Integrating Sphere

Step 3. Sample Loading into Integrating Sphere:

Place both the blank reference and the PLQY test sample into the integrating sphere separately. Ensure vertical insertion to prevent sample displacement. Pay attention to the sample holder orientation, aligning the reflector direction with the excitation light incidence direction.

Figure 3: The PL sample holder is inserted from the top of the integrating sphere. Place the sample in the holder’s groove and position the reflector and sample facing left (toward the excitation light incidence direction).

Step 4. Configuration of PLQY System Parameters

Step 4. Measurement Parameter Adjustment:

First, adjust the excitation light intensity according to measurement requirements using either the mouse-controlled slider or direct power input, where 100% represents full power output. Second, adjust the spectrometer integration time to complement the excitation power settings. Increasing integration time can improve the signal-to-noise ratio (preferably above 100:1), but avoid excessive duration as it may not only extend measurement time but also lead to signal saturation and data distortion.

Figure 4: Software interface for adjusting excitation power output, signal acquisition, and preliminary testing.

The Power control adjusts the excitation light output power via manual input or slider control. The SPM’s Int_Time allows input of the spectrometer integration time. Click the Pre Test button above to examine the spectrum and verify parameter settings.

Step 5. Spectral Measurement

Step 5. Spectral Measurement:

Measure the fluorescence spectra of both blank reference and sample. The blue spectrum represents the blank reference, while the green spectrum shows the PLQY test sample. Due to photoluminescence (PL), the sample spectrum shows lower intensity than the blank reference in the excitation wavelength range, indicating partial absorption of excitation light. In the fluorescence wavelength range, the sample exhibits a fluorescence spectrum while the blank reference shows none.

Figure 5: PLQY measurement software interface.

The left panel shows functions for (A) Blank reference measurement, (B) Sample measurement, and (C) PLQY calculation. In the central spectral display, the blue spectrum represents the blank reference while the green spectrum shows the PLQY test sample. The black dashed line indicates the selected excitation light calculation range, and the orange dashed line shows the selected fluorescence calculation range.

Step 6. One-Click PLQY Calculation with Selected Spectral Ranges

Step 6. One-Click PLQY Calculation with Selected Spectral Ranges:

Select the wavelength ranges for both excitation light and fluorescence calculations, then click the calculate function to obtain the Photoluminescence Quantum Yield (PLQY) value.