Analysis of Carotenoids and Gene Expression in Apple Germplasm Resources Reveals the Role of <i>MdCRTISO</i> and <i>MdLCYE</i> in the Accumulation of Carotenoids

Carotenoids play an important role in the coloring and nutritional value of apple (Malus spp.) fruits. Here, six carotenoids, including lutein, zeaxanthin, β-carotene, β-cryptoxanthin, violaxanthin, and neoxanthin, were detected in 105 fruits of apple germplasm resources, which showed a skewed distribution in both the peel and pulp. There were more carotenoids in the peel than in the pulp, and lutein and β-carotene were the primary carotenoids that were present. The expression levels of most carotenoid pathway genes in germplasm fruits during fruit development were higher in the fruits that had an abundance of carotenoids. A linear relationship analysis showed that the expression levels of MdCRTISO and MdLCYE were highly correlated with the content of carotenoids. The leaves accumulated the greatest number of carotenoids, while the roots had the lowest amount. MdCRTISO and MdLCYE were highly expressed in the fruits compared to other tissues. Transgenic calli and transiently transformed fruits confirmed that MdCRTISO and MdLCYE affected the biosynthesis of carotenoids owing to their effects on the expression of other genes for enzymes in the carotenoid pathway. Our findings will extend the understanding of carotenoid biosynthesis in apple and excavate apple germplasm resources with rich carotenoids to breed high-quality apples

Unraveling the Characteristic Shape for Magnetic Field Effects in Polymer–Fullerene Solar Cells

Spin-dependent effects in organic solar cells (OSCs) are responsible for tuning the electric current when an external magnetic field is applied. Here, we report the magnetic field effect (MFE) on wide-bandgap (WBG) solar cells based on the polymers PBDT­(O)-T1 and PBDT­(Se)-T1 blended with PC₇₀BM. Furthermore, we propose an experimental method based on the electrical transport (<i>i</i>–<i>V</i>) measurements to unveil the negative magneto conductance (MC) at small bias. The observed curves in a double-logarithmic scale display a particular S-like shape, independent of the OSC power conversion efficiency (PCE) or MC amplitudes. Additionally, from the slope of the S-like shape curve, it is possible to identify the fullerene concentrations that would result in the minimum MC and the maximum PCE. Our work opens up a door to find more patterns to describe MFE and PCE in polymer–fullerene solar cells, without the application of external magnetic or luminous sources

PEDOT:PSS-Nafion/n-Si Hybrid Heterojunction TOPCon Solar Cells: Experiment and Simulation

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most popular hole transport materials for replacing traditional high-temperature boron diffusion technology due to its low cost and easy preparation. However, pristine PEDOT:PSS has drawbacks, such as poor work function (WF) and poor film quality, which inhibit the improvement of cell efficiency. According to current research reports, a single dopant can improve only one of these two drawbacks. In this paper, we used Nafion to simultaneously improve the WF and wettability of PEDOT:PSS for preparing novel PEDOT:PSS/n-Si hybrid heterojunction solar cells with a tunnel-oxide passivated contact (TOPCon) back surface field structure, which we call PEDOT:PSS-Nafion (PPN)/n-Si hybrid heterojunction TOPCon solar cell. A cell efficiency of 11.08% was achieved after optimizing the ratio of PEDOT:PSS and Nafion. The three easily improved parameters, namely, series resistance (RS), reflectivity, and WF, were studied and optimized through simulation, achieving a cell efficiency of 20.66%. To reduce RS in the experiment, the Triton X-100-doped PEDOT:PSS film (PPTX) was introduced between the n-Si and PPN films to form highly conductive PPN/PPTX double hole transport layers, and the cell efficiency was increased from 11.08 to 13.7%. The experimental and simulated work presented a new thought and practical guidance for realizing low-cost, easy preparation, and high-efficiency silicon-based solar cells