Numerical study of efficient ternary planar hybrid solar cells using simple boron molecules as organic compounds

Abstract

Ternary solar cells have proven to be a solution to absorb more photons at different wavelengths and reduce the recombination of charge carriers. Here, we propose a new hybrid organic-inorganic ternary planar solar-cell structure using a novel boron compound. The role of this material on the performance of the device with a polymer/borinate/ZnO configuration is studied. As the donor polymer, we evaluate P3HT, PTB7, and PCPDTBT; and three boron compounds with different properties, especially concerning the bandgap and trap energy depth. To validate the experimental electrical characteristics of the borinates, first, we simulate a bilayer structure with C60, subsequently, we simulate and analyze the whole device architecture. The ternary solar cell with PTB7 and a borinate with a bandgap of 1.66 eV and a medium trap energy depth of 0.95 eV above the HOMO level exhibit the highest efficiency, i. e. 11.7%. Furthermore, we present a layer thickness optimization of the materials to reach even higher efficiencies, up to 15.15%. Finally, the effect of the magnitude of the density of trap states in the borinate on the device performance is analyzed.