Study of MAPb(I1−xBrx)3 thin film and perovskite solar cells based on hole transport material-free and carbon electrode

Perovskite solar cells (PSCs) based on hole-transporting-materials (HTM)-free and carbon electrodes have attracted intensive attention due to their low material cost, simple manufacturing process, and high stability. However, their power conversion efficiencies (PCE) need further improvement. In this work, the effect of Br-component x on properties of the MAPb(I1−xBrx)3 thin films as well as photovoltaic performance of PSCs were studied. The MAPb(I1−xBrx)3 thin films were prepared using two-step solution deposition method in ambient air. The Br− component x was varied from 0 to 1 by changing the PbBr2 to PbI2 molar ratio in the precursor solution. PSCs based on the HTM-free and carbon electrodes were fabricated in ambient air in this work, aiming to realize reduction of fabrication cost and improve the stability of PSCs. The results indicated that when Br− component x increase, the XRD diffraction peaks of MAPb(I1−xBrx)3 thin films continuously shift to larger diffraction angle, meanwhile, the absorption edge and PL peak continuously shift toward to the shorter wavelength. The PSCs based on MAPbI2.7Br0.3 exhibits an optimal photovoltaic performance, yielding Voc of 0.95 V, Jsc of 17.61 mA/cm-2, FF of 0.70, and PCE of 11.70%. Its PCE remains 93.3% of the initial efficiency after being exposed in the atmosphere for 700 h.