Enhancement of polymer solar cell performance under low-concentrated sunlight by 3D surface-engineered silicon nanocrystals

Influence of surface engineering of free standing silicon nanocrystals (Si-ncs) by an atmospheric-pressure microplasma treatment without using large organic molecules or surfactants on performance of organic solar cells is demonstrated. Namely, conducted surface engineering allows achieving Si-ncs hydrophilicity, enhanced dispersion and carrier transport in water soluble poly-(3,4-ethylenedioxythiophene doped by poly(4-styrenesulfonate) (PEDOT-PSS). We present results on a nanocomposite formed by Si-ncs/PEDOT-PSS which has shown to be advantageous for polythieno[3,4-b]thiophenebenzodithiophene (PTB7)/[70]PCBM polymer solar cells under low-concentrated sunlight (<10 suns). We demonstrate how the presence of stabilized and highly room-temperature photoluminescent Si-ncs allows the enhancement of the PTB7/[70]PCBM bulk heterojunction solar cell performance via the conversion of high energy photons (<450 nm) into red emission (∼680 nm). Presence of luminescent Si-ncs has played a key role in preventing the degradation of PTB7 photoconductive properties via high energy photons.