Pyrolysis

The biomass from senesced wild‐type plants and T3 homozygous C4H::qsuB lines was used to determine lignin content and composition. Biomass was extracted sequentially by sonication (20 min) with 80% ethanol (three times), acetone (one time), chloroform–methanol (1:1, v/v, one time) and acetone (one time). The standard NREL biomass protocol was used to measure lignin content (Sluiter et al., 2008). The chemical composition of lignin was analysed by pyrolysis‐gas chromatography (GC)/mass spectrometry (MS) using a previously described method with some modifications (Del Río et al., 2012). Pyrolysis of biomass was performed with a Pyroprobe 5200 (CDS Analytical Inc., Oxford, PA, USA) connected with GC/MS (Thermo Electron Corporation with Trace GC Ultra and Polaris‐Q MS) equipped with an Agilent HP‐5MS column (30 m × 0.25 mm i.d., 0.25 μm film thickness). The pyrolysis was carried out at 550 °C. The chromatograph was programmed from 50 °C (1 min) to 300 °C at a rate of 30 °C/min; the final temperature was held for 10 min. Helium was used as the carrier gas at a constant flow rate of 1 mL/min. The mass spectrometer was operated in scan mode and the ion source was maintained at 300 °C. The compounds were identified by comparing their mass spectra with those of the NIST library and those previously reported (Del Río and Gutiérrez, 2006; Ralph and Hatfield, 1991). Peak molar areas were calculated for the lignin degradation products, and the summed areas were normalized.

All perovskite samples were prepared
following the method described in our previous work.^{29 (link)} In summary, FTO substrates were cleaned using RBS detergent,
ethanol, and acetone in an ultrasound bath during several steps of
30 min. Compact TiO₂ was deposited by spray pyrolysis at
450 °C, obtaining an anatase compact layer of around 20–30
nm of thickness. On top of this layer, 50 μL of a TiO₂-mp solution was spin-coated at 4000 rpm, with an acceleration of
2000 rpm/s, during 10 s and sintered at 450 °C during 30 min
in air, forming a mesoporous scaffold of TiO₂ nanoparticles.
After that, 100 μL of 35 mM lithium bistrifluoromethanesulfonimidate
(Li-TFSI) in acetonitrile was spin-coated (3000 rpm for 10 s) and
the substrates were thermally annealed again in air at 450 °C
for 30 min. After this process, the substrates were brought directly
into a glovebox.
Perovskite precursor solutions and thin films
were prepared inside a N₂-filled glovebox. Two master solutions
were prepared in advance: (a) 0.9 M PbI₂ and 0.9 M FAI
and (b) 0.9 M PbI₂ and 0.9 M CsI. The final solution was
prepared right before deposition by pouring solution (a) into solution
(b) in the proportion a:b = 83:17, obtaining a perovskite final composition
of Cs_0.17FA_0.83PbI₃. The solvent
was anhydrous DMF:DMSO (4:1) for all solutions. FA salts were bought
from Dyesol, lead salts from TCI, solvents from Fisher, and the remaining
chemicals from Sigma-Aldrich. All chemicals were used as received
without further treatment. Seventy-five microliters of the precursor
solution was spread over the substrate and spin-coated using a two-step
program. The first step used a rotation speed of 1000 rpm with an
acceleration of 200 rpm/s for 10 s, followed by a second step in which
the films were spun at 6000 rpm for 15 s using an acceleration of
2000 rpm/s. After 20 ss, 200 μL of anhydrous chlorobenzene was
applied on the spinning film. Directly after spin coating, the films
were annealed on a hotplate at 100 °C for approximately 1 h.
The polymer P3 was synthesized according to the method described
previously.^{35 (link)} For deposition, a P3 solution
with a concentration of 5 mg/mL in chlorobenzene was prepared and
stirred in the ambient environment to fully dissolve the polymer and
then spin-coated onto the perovskite or FTO substrates at 3000 rpm
for 30 s.
Gold electrodes were evaporated using a Leica EM MED020
thermal
evaporator at a pressure below 7 × 10^–3 mbar.
The thickness was measured using a Leica EM QSG100 quartz microbalance.
To avoid short circuits, a mask was used to prevent any gold deposition
on the side opposite to the etched substrate. A 7 nm gold layer was
deposited using this mask; thereafter, the chamber was vented, and
an additional mask was added for the evaporation of the thick (>50
nm) gold contact and the bus bars.

Five cotton bolls were randomly selected from each replicate samples of the cultivated G. arboreum A₂-100 and G. hirsutum TM-1 as well as wild G. raimondii D₅-31. Two replicated samples of the dried cotton fibers of G. raimondii D₅-31, G. arboreum A₂-100, and G. hirsutum TM-1 were cut in a Wiley mill into 20 mesh. Average contents of each cotton variety were obtained by measuring the randomly selected cotton bolls from two biological replicates. Lignin analysis was performed with pyrolysis molecular beam mass spectroscopy (pr-MBMS) by Complex Carbohydrate Research Center (CCRC) at University of Georgia. Duplicated cotton samples along with control samples including NIST 8492 (lignin content, 26.2%) and aspen standards were pyrolyzed at 500°C and the volatile compounds were analyzed for lignin using a molecular beam mass spectrometer (Extrel Core Mass Spectrometers). The raw data were processed through UnscramblerX 10.1 software to obtain the principal components and raw lignin data. G. arboreum A₂-100 fibers exclusively composed of cellulose (95.6~100%) with the lowest lignin level among cotton species was also used as the lignin base line for all tested cotton samples.