No abstract

Poly(3,: polystyrene sulfonate (PE-DOT:PSS) is usually used as a hole-selective contact layer in photovoltaic and optoelectronic fields due to its good film-forming property and low cost. However, PSS as a dispersant is an insulating material that restricts the conductivity of PEDOT:PSS films. In this work, we modified the PEDOT:PSS solution by heat treatment to realize the double improvement of the conductivity and work function of the PEDOT:PSS film for PEDOT:PSS/Si hybrid solar cells (HSCs). It was found that phase separation occurs in the process of heat treatment of the PEDOT:PSS solution, which causes the dispersed PEDOT to agglomerate into strips to form a conductive grid. By optimizing the heat treatment temperatures, the electrical conductivity of the PEDOT:PSS film increased from 1090 to 1305 S/cm at 90 °C. In addition, the composition of the PEDOT:PSS solution was changed to increase the value of PEDOT/PSS by 55.12%, which increased the work function of the PEDOT:PSS film from 4.5 to 4.8 eV. After calculation with the finite volume method, the band bending at the Si surface of heterogeneous contact increased by 0.216 eV, which is more conducive to carrier separation. Finally, the power conversion efficiency of the heat-treated PEDOT:PSS solution applied to PEDOT:PSS/Si HSCs increased from 11.03 to 12.38% compared to that of nonheat-treated PEDOT:PSS/Si HSCs.

Silicon nanowire (SiNW) array transparent solar cells (TSCs) have the advantages of flexibility and visible transparency for a wider application of transparent photovoltaics. The photoelectric performance of SiNW array TSCs is mainly determined by the single SiNW. In this work, a single SiNW is designed to obtain ultrahigh extinction for improving the light absorption and the power conversion efficiency of SiNW array TSCs. According to the analysis of the dipole near-field interaction, the extinction of a single SiNW is strongly related to the relationship between the polarization direction of the incident light and the SiNW scale. When the incident light is linearly polarized, increasing the scale in the polarization direction enhances the extinction, and increasing the scale in the vertical direction of polarization reduces the extinction. Furthermore, optimizing the symmetry of the SiNW achieves a good extinction of natural light and obtains a SiNW with a trilobal top view to improve the extinction of the single SiNW by 85%. Compared with cylindrical SiNW array TSCs, the light absorption increased by 23%, and the power conversion efficiency increased by 14.7%.

In order to improve the utilisation rate of renewable energy and flexibility of the system, the AC-DC distribution network with multiple park integrated energy subnetwork (PIESN) based on multi-port power electronic transformer (MPPET) is proposed. First, a power-sharing model of interconnected PIESNs based on MPPET is built, in which the port power of MPPET can be controlled. Then the flexibility demand and supply of electricity, heat and cooling are analysed and a flexibility-sharing model among multi-PIESN is established. Multi-energy flexibility conversion mechanism is proposed and the flexibility index is established. Moreover, the optimal operation problem is formulated and solved. The objective function is the comprehensive operation cost, which includes generation cost, energy cost of PIESN, network loss cost, MPPET loss cost, carbon emission cost and electricity storage system operation cost. Finally, simulation on the modified IEEE33 system shows that the proposed model can make the system be in an adequate flexibility, improve the utilisation rate of renewable energy, reduce load shedding and realise the power sharing among multi-PIESNs.

PEDOT:PSS/Si hybrid solar cells have attracted wide attention due to the fabrication of an inversion layer near the Si surface by a solution method to realize high efficiency. However, Si dangling bonds on the Si surface produce surface states and lattice mismatches to deteriorate the performance of the solar cells. In this work, the aromatic rubrene is used to modify the Si dangling bonds to passivate the Si surface for improving the junction quality of PEDOT:PSS/Si. It is found that the interaction of rubrene with Si dangling bonds reduces the binding energies of Si 2p 1/2 and Si 2p 3/2 by 0.2 and 0.1 eV, respectively. These large shifts of Si 2p core levels are the signals that form a stronger inversion layer for a higher quality junction. In addition, rubrene increases the work function of the PEDOT:PSS film by 0.09 eV to increase the band bending of the Si interface to promote carrier separation. Finally, the power conversion efficiency (PCE) of PEDOT:PSS/Si hybrid solar cells with rubrene is 12.59%, which is 23.92% higher than that without rubrene.