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

Abstract

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 roomtemperature 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.Index Terms -silicon nanocrystals, surface engineering, polymer solar cells, low concentrator sunlight.

Improved Optoelectronic Properties of Silicon Nanocrystals/Polymer Nanocomposites by Microplasma-Induced Liquid Chemistry

“…Overall, microplasma processing has produced a mechanically stable, well-dispersed SiNCs/polymer nanocomposite with improved morphology leading to enhanced transport and photosensitivity. The enhanced conductivity and photosensitivity of this water-soluble organic/inorganic nanocomposite can as a result be very useful in many different applications; as an example, we have applied this process as a protective/enhancing top layer for organic solar cells with clear improvements in the device performance. , …”

“…The enhanced conductivity and photosensitivity of this water-soluble organic/inorganic nanocomposite can as a result be very useful in many different applications; as an example, we have applied this process as a protective/ enhancing top layer for organic solar cells with clear improvements in the device performance. 61,62…”

A silicon nanocrystal/polymer nanocomposite as a down-conversion layer in organic and hybrid solar cells

“…Therefore, the use of highly photoluminescent and surface-engineered Si-ncs represents an attractive option for the management of UV-photons and high photon fluxes through three different but closely linked mechanisms [10]. Firstly, Si-ncs absorption in the UV region prevents high energy photons reaching the polymeric active layer reducing UV-induced degradation; secondly, undesired high-energy photons are converted into useful lower energy ones via room temperature PL [11,12]. Thirdly, the PL of Si-ncs is expected to be enhanced under high intensity radiation [10] so that the blue-to-red photon conversion becomes even more efficient under high photon fluxes or concentrated light.…”

“…10 Firstly, Si-nc absorption in the UV region prevents high energy photons reaching the polymeric active layer reducing UV-induced degradation; secondly, undesired high-energy photons are converted into useful lower energy ones via room temperature PL. 11,12 Thirdly, the PL of Si-ncs is expected to be enhanced under high intensity radiation 10 so that the blue-to-red photon conversion becomes even more efficient under high photon fluxes or concentrated light. It is clear that organic devices are not suitable for technologies based on highly concentrated light and are not expected to compete with III-V layers which typically use 300-500 suns.…”

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

“…While the durability of these devices has also drastically improved, the organic composition still suffers from ultraviolet-induced degradation. The use of luminescent and stable inorganic nanocrystals that absorb efficiently in the UV range represents a possible opportunity to overcome this drawback of polymer devices [1][2][3]. Particularly, silicon nanocrystals (Si-ncs) with quantum confinement effects absorb well in the UV and have strong room temperature photoluminescence (PL) in the visible range, so that the use of Si-ncs for down-conversion represents an appealing approach.…”