Optimizing the performance of Ge-based perovskite solar cells by doping CsGeI3 instead of charge transport layer

Abstract

In recent years, Ge-based perovskite solar cells (PSCs) have gradually become a shining star in the field of scientific research because of their high conductivity. However, the defects between battery layers seriously affect the transmission efficiency of carriers. Therefore, we doped CsGeI3 instead of the original charge transport layer to passivate the defects of the battery. We created p-CsGeI3 layer and n-CsGeI3 layer on both sides of i-RbGeI3, which improved the energy level matching between i-RbGeI3 layer and the contact materials on both sides, and then facilitated the carrier transmission. We also added two interface defect layers (IDL) in order to be able to quantify the various adverse reactions at the interface, which reduces the recombination of carriers. We compared different electrode materials, and found that the appropriate metal work function can maximize the carrier transmission efficiency. We designed a structure of CsGeI3 instead of charge transport layer, and optimized the basic parameters of the battery with SCAPS. Reasonable thickness display can not only improve the absorption rate of photons, but also significantly reduce the recombination rate. Excessive trapping density increases electron/hole recombination, which is not conducive to carrier transportation. The appropriate band gap improves the matching degree of energy levels of each layer, and then promotes the transport of carriers between interfaces. At high temperature, more strain is generated inside the battery, which causes the crystal structure of the battery to deform. The high doping concentration strengthens the internal potential and promotes the carrier migration. The efficiency of the battery reached 34.96%, and the efficiency of other batteries with the same structure was less than 20%. Our research proved the great potential of doping CsGeI3 to construct all perovskite solar cell structures.