Background:
Drought is a major factor that limits crop productivity worldwide. Traditional breeding techniques have not been successful in developing crops that can tolerate prolonged drought. Genetic engineering has been explored as an alternative approach for developing drought-tolerant crops. However, most of the genes that have been identified for drought tolerance are from non-crop species, and their effectiveness in crop plants is limited due to differences in gene regulation and expression.
Article Summary:
In an article published in the journal Nature Communications, researchers from the University of Maryland describe a synthetic biology approach for developing drought-tolerant crops. The researchers used a transcription factor, named NAC089, which is known to regulate drought stress responses in Arabidopsis thaliana, a model plant species. The researchers modified the NAC089 gene to increase its activity and stability, and introduced it into maize plants using a tissue-specific promoter that is active in the roots.
The researchers found that the transgenic maize plants expressing the modified NAC089 gene showed improved drought tolerance compared to wild-type maize plants. The transgenic plants had a higher survival rate under drought stress, as well as increased biomass and yield. The researchers also found that the modified NAC089 gene regulated the expression of a set of genes involved in stress responses and plant growth, which may contribute to the improved drought tolerance observed in the transgenic plants.
Key Points:
Figure 1. (a) XRD spectra of DMF/DMSO wet films in spinning process #: PbI2-DMSO intermediate phase; *: PbI2-NMP intermediate phase. (b) DMF/NMP wet films in spinning process. (c) Optical photographs of two different solvent systems. (d) DFT calculation of interaction between DMF and different solvents (DMSO & NMP). (e) Schematic illustration of the two different solvent system without anti-solvent assisted while spinning process (Above: DMF/DMSO system; Below: DMF/NMP system).
Influence of interaction between co-solvents and perovskite components on PVK morphology
After determining the rule that co-solvents with weak interaction with the main solvent can achieve spontaneous regulation of solute concentration, in order to compare and find the most suitable co-solvent, MCP and DMI were used as two solvents with structures extremely similar to NMP to prepare perovskite films with the main solvent DMF, and simulation calculations were also used to compare the interaction forces between solvents. The results showed that the effect of DMI as a co-solvent should be the best among the three, but this is not the case in reality. The DMI-spun film appeared whitish and showed a dull gray color after annealing, with large pores clearly visible on the surface in SEM images. Further comparison of the interaction between different co-solvents and the main solutes (PbI2, FAI) through FTIR showed that NMP had a stronger hydrogen bonding interaction with the two main components compared to the other two solvents, and therefore could obtain a better perovskite film morphology during the rapid solvent evaporation process.
Figure 2. (a) DFT calculation of interaction between DMF and different solvents (MCP and DMI). (b) XRD spectra of three kinds of wet films (DMF/MCP, DMF/NMP, DMF/DMI) after spinning process (c) FTIR spectra of MCP, MCP mixed with PbI2, MCP mixed with FAI and (d) NMP, NMP mixed with PbI2, NMP mixed with FAI, (e) DMI, DMI mixed with PbI2, DMI mixed with FAI. (f-h) SEM images of three kinds of perovskite films made by different solvent systems after annealing.
By using the optimal co-solvent NMP and without using anti-solvent, a power conversion efficiency (PCE) of 22.00% with a fill factor (FF) of 80.11% for small active area (0.07 cm2) and 18.02% PCE with 70.8% FF for large active area (1 cm2) were achieved through this strategy. Based on this, a 5×5 cm2 sized perovskite solar cell module consisting of seven sub-cells in series was designed and prepared, which showed a PCE of 16.54% (open-circuit voltage of 7.57 V and FF of 77.09%). PSCs based on NMP demonstrated high repeatability and good stability (still maintaining 80% of PCE after 30 days of storage under ambient conditions). This strategy provides a simple and effective method for the preparation of efficient and stable perovskite solar cells and modules, promoting their large-scale commercial application.
Figure 3. (a) Schematic diagram of the planar n-i-p structure perovskite solar cells. (b) J-V curves of champion performance PSCs fabricated from different solvents. (c) Statistics of efficiencies for the devices fabricated from DMF/NMP and DMF/DMI. (d) J-V curves of champion performance PSC in 1cm2 active area fabricated from DMF/NMP system. (e) EQE spectra of PSCs based on DMF/NMP solvent system. (f) Steady-state photocurrent for DMF/NMP devices at the maximum power point under AM 1.5G illumination.
Figure 4. (a) Schematic diagram of 5×5 perovskite mini-module fabricated from anti-solvent free strategy. (b) Champion J-V curves of module fabricated from DMF/NMP. (c) Photograph of 5×5 cm2 mini-module.
Source:https://onlinelibrary.wiley.com/doi/full/10.1002/smll.202301323
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