In this work, semi-transparent inverted polymer solar cells with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate; PEDOT:PSS) top electrodes were fabricated by spin-coating process. Poly(3-hexylthiophene; P3HT):[6,6]-phenyl C61-butyric acid methyl ester (PCBM) was used as a model material combination for a bulk heterojunction solar cell, because this material combination has been frequently studied, and its properties and performance have been well established. For enhancing the wetting of P3HT:PCBM blend film, different plasma etching conditions were tried. In addition, different high boiling point organic additives were tried to enhance the conductivity of PEDOT:PSS. The performance of solar cells with different fabrication conditions for the top electrode was compared. The best performance was obtained for Ar plasma etching to improve wetting of PEDOT:PSS and the addition of ethylene glycol to improve conductivity.
We performed a systematic study of the effect of processing conditions on the performance of P3HT:PCBM solar
cells. We have investigated the influence of the source material, solution preparation (stirring vs. sonication),
additives (such as 1,8-octanedithiol), pre-formation of P3HT nanowires, and annealing on the device performance
and/or morphology and phase separation in the active layer. Furthermore, the influence of spin-coating PCBM on
top of P3HT and PCBM on top of the P3HT:PCBM layer has been investigated. We found that all of these factors
affect the performance of the solar cells, although there are several alternative methods which can result in similar
improvements of the performance. We found that the improvement trends for various procedures (additives, PCBM
top layer, P3HT nanowires, etc.) are similar and also strongly dependent on the different source materials. The main
factor determining in the obtainable efficiency is the solution preparation and the source materials. Obtained results
and the implications on further improvement of solar cell performance are discussed in detail.
Nanostructures of the tin oxide, indium oxide and tin-doped indium oxide have been fabricated on silicon by chemical
vapor deposition from a mixture of metal oxide nanoparticles and single-wall carbon nanotubes (SWCNT). Different
ratios of the metal oxide to SWCNT have been used. It was found that the morphology of the nanostructures depends on
the substrate temperature. The morphology, growth direction and optical properties have been studied by scanning
electron microscopy, transmission electron microscopy and photoluminescence spectroscopy.
Organic photovoltaic (OPV) devices have attracted much interest in recent decades because they have a great potential
for low cost solar cells. Among different kinds of organic solar cells, conjugated polymer/fullerene bulk heterojunction
(BHJ) solar cells have exhibited improvements in the power conversion efficiency (PCE) in recent years. The
performance of BHJ solar cells is highly dependent on different fabrication processes. To address this issue, we focus on
the dependence of different photovoltaic parameters on the fabrication methods. BHJ solar cells fabricated using
platinum metallopolyyne (P1) with a low band gap of 1.85 eV as an electron donor and phenyl-C61-butyric acid methyl
ester (PCBM) as an electron acceptor have been studied. The fabrication parameters, such as ratios of P1 to PCBM,
solvents used, thickness of the active layers and top contact materials, have been systematically investigated. Blend ratio
and solvent used had most significant influence on photovoltaic performance with several times higher efficiency of the
best condition compared to the worst condition. They affected all photovoltaic parameters [open circuit voltage (V<sub>oc</sub>),
short circuit current density (J<sub>sc</sub>) and the fill factor (FF)]. Top contact materials affected the V<sub>oc</sub> and the FF, while
thickness of the active layer mainly affected the J<sub>sc</sub> and FF. The influence of different fabrication conditions on
photovoltaic performance has been discussed.