Asymmetric fused-ring electron acceptors (a-FREAs) have proved to be a promising type of electron acceptor for high-performance organic solar cells (OSCs). However, the relationship among molecular structures of a-FREAs and their nanoscale morphology, charge-carrier dynamics, and device performance remains unclear. In this contribution, two FREAs differing in conjugated backbone geometry with an asymmetric conformation (IPT-2F) or symmetric one (INPIC-2F) are selected to systematically explore the superiorities of the asymmetric conformation. Despite the frailer extinction coefficient and weaker crystallinity, IPT-2F shows stronger dipole interactions in the asymmetrical backbone, which would induce a closer lamellar packing than that of the symmetrical counterpart. Using PBDB-T as the electron donor, the IPT-2F-based OSCs achieve the best power conversion efficiency of 14.0%, which is ca. 67% improvement compared to the INPIC-2F-based ones (8.37%), resulting from a simultaneously increased short-circuited current density (Jsc) and fill factor. Systematical investigations on optoelectronic and morphological properties show that the asymmetric conformation-structured IPT-2F exhibits better miscibility with the polymer donor to induce a favorable blend ordering with small domain sizes and suitable phase separation compared to the INPIC-2F symmetric molecule. This facilitates an efficient charge generation and transport, inhibits charge-carrier recombination, and promotes valid charge extraction in IPT-2F-based devices.
The organic-metal halide perovskite solar cells have recently shown the high power conversion efficiency (PCE) exceeding 20%. A better understanding of the relationships between material parameters, device architectures, and performance is still required for the continued development of the perovskite solar cells. Three types of architectures are simulated with the program 1-D device simulation program for the analysis of microelectronic and photonic structure. The hole transport material-free MAPbI 3 solar cells attain the simulated PCE of 24.1%. A maximum PCE of 26.60% and a maximum V OC (open-circuit voltage) of 1.83 V for FTO/ZnO/MAPbX 3 (X = I and Br)/CuSCN/Au-based solar cells are predicted, respectively. The FTO/ZnO/MAPbI 3 /MAPbBr 3 /CuSCN/Au-based solar cells first designed possesses a characteristic of tunable PCE and V OC by changing the thicknesses of MAPbI 3 and MAPbBr 3 , and the PCE of 27.50% (J SC = 26.17 mA/cm 2 , V OC = 1.19 V, and FF = 0.88) was obtained. These simulation results can help researchers to reasonably choose materials and optimally design high-performance perovskite solar cells.
In this article, researchers have investigated the design and capability optimisation of SMPS with a particular emphasis on increasing the efficiency of power transfer and developing new manufacturing techniques. Nowadays, the PV industry mostly depends on silicon base technique, but it has many advantages such as high cost, low flexibility and great environment impact. By comparison, the structure of small molecular materials is easily duplicated and has a promising future in the field of PV devices. In this paper, this paper present a discussion on how to increase energy conversion efficiency by using SMPS, as well as the high efficiency of all SMPS systems. In addition, this paper also proposes methods and theoretical frameworks for optimizing material structures using experimental design and machine learning. Not only do they contribute to the improvement of material properties, but they also provide significant theory and practice support for developing highly efficient PV devices.
Using the photovoltaic spectral response of epitaxial P-N junction, the paper suggests a method of determining the minority carrier diffusion length in N layer of N/P epitaxial silicon wafer. The authors made a group of diagrams which contained the information of minority carrier diffusion lengths in the epitaxial layer and the substrate according to the theoretical analysis. When there is a thermal SiO2 thin film on the surface of the sample, the photovoltage of the sample depends on the characteristics of the epitaxial P-N junction. The incident photon intensity I versus reciprocal absorption coefficient 1/a curve is measured by the same method andsame apparatus as that of the SPV method, and the value of isevaluated on the I-1/a curve. Then the hole diffusion length in N epitaxial layer is calculated from the given diagrams. The experimental results show that the method is reasonable.
Perovskites are attracting attention for optoelectronic devices. Despite their promise, the large-scale synthesis of perovskite materials with exact stoichiometry, especially high-entropy perovskites, has been a major challenge. Moreover, the difficulty in stoichiometry control also hinders the development of perovskite X-ray flat-panel detectors. Previous reports all employed simple MAPbI3 as the active layer, while the performance still falls short of optimized single-crystal-based single-pixel detectors. Herein, a scalable and universal strategy of a mechanochemical method is adopted to synthesize stoichiometric high-entropy perovskite powders with high quality and high quantity (>1 kg per batch). By utilizing these stoichiometric perovskites, the first FA0.9 MA0.05 Cs0.05 Pb(I0.9 Br0.1 )3 -based X-ray flat-panel detector with low trap density and large mobility-lifetime product (7.5 × 10-3 cm2 V-1 ) is reported. The assembled panel detector exhibits close-to-single-crystal performance (high sensitivity of 2.1 × 104 µC Gyair-1 cm-2 and ultralow detection limit of 1.25 nGyair s-1 ), high spatial resolution of 0.46 lp/pixel, as well as excellent thermal robustness under industrial standards. The high performance in the high-entropy perovskite-based X-ray FPDs has the potential to facilitate the development of new-generation X-ray-detection systems.
Most of the systematic studies on tuning the band gap in the family of organolead halide perovskites have focused on changing the compositions of halogens. Here, the effects of varying the organic content on the band gap of CH3NH3PbI3 were studied. The methylammonium lead iodide (CH3NH3PbI3) films were fabricated with different molar ratios of CH3NH3I to PbI2. We found that the films become compact and the crystalline size decreased from 6.0 to 0.2 μm and the optical band gap of CH3NH3PbI3 could be transferred from direct to indirect with increasing CH3NH3I content in the precursor. The experimental results demonstrated that the existence of the indirect band gap in CH3NH3PbI3 film and the CH3NH3I content plays a key role in adjusting the film morphology and optical band. The investigation of the optical band transition induced by changing organic content could provide a different view on studying CH3NH3PbI3 materials.
The existence of serious hysteresis effect for regular perovskite solar cells (PSCs) will affect their performances, however, the inverted PSCs can significantly suppress the hysteresis effect. To data, it has been very rarely reported to simulate the inverted planar heterojunction PSCs. In this paper, the effects of hole transport material (HTM), electron transport material (ETM), and ITO work function on performance of inverted MAPbI<sub>3</sub> solar cells are carefully investigated in order to design the high-performance inverted PSCs. The inverted MAPbI<sub>3</sub> solar cells using Cu<sub>2</sub>O, CuSCN, or NiO<i><sub>x</sub></i> as HTM, and PC<sub>61</sub>BM, TiO<sub>2</sub>, or ZnO as ETM are simulated with the program AMPS-1D. Simulation results reveal that i) the inverted MAPbI<sub>3</sub> solar cells choosing NiO<i><sub>x</sub></i> as HTM can effectively improve the photovoltaic performance, and the excellent photovoltaic performance obtained by using TiO<sub>2</sub> as ETM is almost the same as by using ZnO as ETM; ii) the ITO work function increasing from 4.6 eV to 5.0 eV can significantly enhance the photovoltaic performances of Cu<sub>2</sub>O— based and CuSCN— based inverted MAPbI<sub>3</sub> solar cells, and the NiO<i><sub>x</sub></i>— based inverted MAPbI<sub>3</sub> solar cells have only a minor photovoltaic performance enhancement; iii) based on the reported ITO work function between 4.6 eV and 4.8 eV, the maximum power conversion efficiency (PCE) of 27.075% and 29.588% for CuSCN— based and NiO<i><sub>x</sub></i>— based inverted <i>MA</i>PbI<sub>3</sub> solar cells are achieved when the ITO work function reaches 4.8 eV. The numerical simulation gives that the increase of hole mobility in CuSCN and NiO<i><sub>x</sub></i> for ITO/CuSCN/MAPbI<sub>3</sub>/TiO<sub>2</sub>/Al and ITO/NiO<i><sub>x</sub></i>/MAPbI<sub>3</sub>/TiO<sub>2</sub>/Al can greatly improve the device performance. Experimentally, the maximum hole mobility 0.1 cm<sup>2</sup>·V<sup>–1</sup>·s<sup>–1</sup> in CuSCN restricts the photovoltaic performance improvement of CuSCN— based inverted MAPbI<sub>3</sub> solar cells, which means that there is still room for the improvement of cell performance through increasing the hole mobility in CuSCN. It is found that NiO<i><sub>x</sub></i> with a reasonable energy-band structure and high hole mobility 120 cm<sup>2</sup>·V<sup>–1</sup>·s<sup>–1</sup> is an ideal HTM in inverted MAPbI<sub>3</sub> solar cells. However, the increasing of electron mobility in TiO<sub>2</sub> cannot improve the device photovoltaic performance of inverted MAPbI<sub>3</sub> solar cells. These simulation results reveal the effects of ETM, HTM, and ITO work function on the photovoltaic performance of inverted MAPbI<sub>3</sub> solar cells. Our researches may help to design the high-performance inverted PSCs.
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