Design and Development of D-A-D Organic Material for Solution-Processed Organic/Si Hybrid Solar Cells with 17.5% Power Conversion Efficiency

Abstract

Organic/silicon hybrid solar cells have attracted much interest due to their cheap fabrication process and simple device structure. A category of organic substances, Dibenzothiophene–Spirobifluorene–Dithiophene (DBBT-mTPA-DBT), comprises dibenzo [d,b] thiophene and 3-(3-methoxyphenyl)-6-(4-methoxyphenyl)-9H-Carbazole, which function as electron donors. In contrast, methanone is an electron acceptor, with an ∆Est of 3.19 eV. This work focused on hybrid solar cells based on the guest–host phenomena of DBBT-mTPA-DBT and CBP. Using a Si/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) hybrid solar cell with an ultra-thin Dibenzothiophene–Spirobifluorene–Dithienothiophene (DBBT-mTPA-DBT) interlayer between Si and Al led to a PCE of 17.5 ± 2.5%. The DBBT-mTPA-DBT interlayer substantially improved the Si/Al interface, reducing contact resistance from 6.5 × 10⁻1 Ω·cm2 to 3.5 × 10⁻2 Ω·cm2. This improvement increases electron transport efficiency from silicon to aluminum and reduces carrier recombination. The solar cell containing the DBBT-mTPA-DBT/Al double-layer cathode shows a 10.85% increase in power conversion efficiency relative to the standard Al cathode device.

Keywords

• organic D-A-D material
• Dibenzothiophene–Spirobifluorene–Dithiophene
• hybrid photovoltaic cell
• contact optimization
• dibenzo [d,b] thiophene
• 3-(3-methoxyphenyl)-6-(4-methoxyphenyl)-9<i>H</i>-Carbazole