V 670 spectrometer

All solvents and chemicals of reagent grade were used without purification except tetra-n-butylammonium phosphate (n-Bu₄NPF₆), which was recrystallized from methanol. 4-Aminotriphenylamine [59 (link)], 4,4’-dimethoxy-4’’-nitrotriphenylamine [38 (link)], 4,4’-dimethyl-4’’-nitrotriphenylamine [60 (link)], and n-Bu₄NBArF₄ [61 (link)] were synthesized as described in the literature. A JASCO V-670 spectrometer was used for UV–vis-NIR measurements at room temperature. The ¹H NMR spectra were recorded using a JEOL JNM-ECP400 spectrometer with tetramethylsilane (TMS) as internal standard (0 ppm). EIMS measurements were performed using a JEOL JMS-700 MStation spectrometer.

The UV–vis
measurements were conducted with a V670 spectrometer from Jasco, equipped
with a photomultiplier tube (PMT) and a Peltier-cooled PbS detector
in transmission mode. The transmission spectra were corrected for
a dark-count spectrum and referenced to a baseline spectrum of the
employed solvent.
The PL spectra were recorded with a Fluorolog
iHR 320 Horiba Jobin Yvon spectrometer from Horiba Scientific fitted
with a PMT detector. The PL emission was determined by finding the
emission wavelength λ_emission with a maximum PL intensity.
Time-resolved PL measurements were performed with a FluoTime 300
spectrometer from PicoQuant equipped with a TimeHarp 260 PICO counting
TCSPC unit and a 355 nm pulsed PicoQuant laser. Samples were prepared
by spin-coating or drop-casting of solutions containing QDs (∼0.1
mg/mL) and organic dyes (concentrations indicated in figure legends).
Donor decay traces were recorded at the PL peak center by using an
emission monochromator.

¹H NMR (500 MHz) and ¹³C NMR (126 MHz) spectra of the compounds were recorded on a Bruker AVANCE III HD spectrometer. Chemical shifts were reported as the delta scale in p.p.m. relative to CDCl₃ (δ=7.26 p.p.m.) for ¹H NMR and CDCl₃ (δ=77.16 p.p.m.) for ¹³C NMR. ¹H and ¹³C NMR spectra are provided for compounds; see Supplementary Figs 1–10. Ultraviolet/Vis/near-infrared spectroscopy (NIR) absorption spectra were recorded on a Shimadzu UV-2550 or JASCO V670 spectrometer. Mass spectra were recorded on a Bruker microTOF using electrospray ionization (ESI)-time-of-flight method for acetonitrile solutions. Unless otherwise noted, materials obtained from commercial suppliers were used without further purification.

UV−Vis absorption spectra were measured using JASCO V-670 spectrometer. The XRD measurements were performed on a 2D Phaser equipment (Bruker, Madrid, Spain), with Cu-Kα radiation working at 30 kV and 10 mA, in order to check the crystalline structure of the GO-based materials. Thermogravimetric analysis (TGA) was performed on a TGA Q50 thermogravimetric analyzer (TA Instruments, Cerdanyola del Valles, Spain). Samples (5−10 mg) were weighed in titanium crucibles and heated under a nitrogen atmosphere from 50 to 800 °C at a heating rate of 10 °C min⁻¹. Surface morphologies were obtained by SEM (JSM 6300 JEOL, Tokyo, Japan) equipped with energy-dispersive X-ray spectrometer (EDS, Oxford Instruments, Bristol, UK) for elemental composition measurements. TEM images were acquired using JEM-1010 (JEOL DEBEN AMT, Tokyo, Japan). The presence of functional groups was assessed by means of FTIR. FTIR spectra were acquired on a FT/IR-6200 (Jasco, Madrid, Spain) spectrometer in the spectral window of 4000–400 cm⁻¹ in ATR mode. The structure and composition of GO-based materials were studied by X-ray photoelectron spectroscopy (XPS) with a VG-Microtech Multilab 3000 (Thermo Fisher Scientific Inc., Waltham, MA, USA) photoelectron spectrometer. Potential zeta was recorded using a dynamic laser scattering analyzer (Zetasizer, 2000 HAS, Malvern, Worcestershire, UK).