Surface-engineered silicon nanocrystals as high energy photons downshifters for organic and hybrid solar cells

In this contribution we present an approach to improve organic and hybrid solar cell performance via microplasma-induced surface engineering of silicon nanocrystals (Si-ncs) without using large organic molecules. Surface-engineered Si-ncs were dispersed in aqueous solutions with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and subsequently a hybrid nanocomposite was formed to be used as optical down-converter for blue photons (high energy photons higher ~2.7 eV) into red photons (bellow ~1.8 eV). The integration of the nanocomposite in organic devices enhanced the photocurrent generation under concentrated light and prevented ultra-violet (UV) radiation from reaching the organic active layer, therefore limiting its degradation. In additional devices, Si-ncs at different concentrations were also used in the PTB7:[70]PCBM bulk heterojunction active layer, exhibiting a contribution to carrier generation and exciton dissociation.