Geming Wang

The effects of electron and hole transport layer with the electrode work function on perovskite solar cells

The effects of electron and hole transport layer with the electrode work function on perovskite solar cells with the interface defects were simulated by using analysis of microelectronic and photonic structures-one-dimensional (AMPS-1D) software. The simulation results suggest that TiO2 electron transport layer provides best device performance with conversion efficiency of 25.9% compared with ZnO and CdS. The threshold value of back electrode work function for Spiro-OMeTAD, NiO, CuI and Cu2O hole transport layer are calculated to be 4.9, 4.8, 4.7 and 4.9 eV, respectively, to reach the highest conversion efficiency. The mechanisms of device physics with various electron and hole transport materials are discussed in details. The device performance deteriorates gradually as the increased density of interface defects located at ETM/absorber or absorber/HTM. This research results can provide helpful guidance for materials and metal electrode choice for perovskite solar cells.

Numerical simulation on n-MoS2/p-Si heterojunction solar cells

n-MoS2/p-Si heterojunction solar cells were simulated by using Analysis of Microelectronic and Photonic Structures (AMPS-1D) software. In order to fundamentally understand the mechanism of such kind of cells, the effects of electron affinity, band gap and thickness for MoS2, as well as the donor concentration in Si layer on the devices performance were simulated and discussed in detail. The effects of defect states in Si layer and at n-MoS2/p-Si interface on the performance of devices were also simulated. It is demonstrated that two-dimensional monolayer MoS2 with the highest band gap of 1.8 eV is the optimized option for ideal devices which can give out the highest efficiency over 19.0%. Si layer with higher acceptor concentration is more likely to be recommended in achieving higher power conversion efficiency if defect level can be effectively controlled. The defect states in Si layer and at MoS2/Si interface were identified to influence the performance of the devices significantly.

The role of carbon nanotubes on the capacitance of MnO2/CNTs

The electrochemical behavior of MnO2/carbon nanotubes (CNTs) has been studied by using cyclic voltammetry, galvanostatic charge discharge measurement and electrochemical impedance spectroscopy in 0.5 M Na2SO4 solution. The loading mass of CNTs, the potential sweep rate as well as the frequency have been investigated in detail to make clear of their influence on capacitance, resistance, and relaxation time constant. The dependence of the voltammetric surface charge q* on different loading mass of CNTs and potential scan rate has been investigated. With the addition of CNTs, resistance and relaxation time constant of the material are reduced and the rate capability increased. In particular, CNTs is beneficial for the outer surface capacitance contribution of MnO2. The outer surface capacitance contribution of MnO2/CNTs (1: 1) can reach 67% total capacitance contribution.