Constructing a Solar Cell Based on n and p –type Polymers and Improve its Characteristics Using mWCNT

Abstract

In this work, solar cells were constructed based polymers prepared as n-type and p-type. Eight polymers were prepared from the reaction of P-phenylene-diamine with carbon disulfide and sulfur by polymerization. The IR, XDR, and thermal history of polymers were studied at room temperature, with thicknesses between (0.7-0.6) mm. Also, Hall factor, the mobility for electrons and holes before and after doping were studied. The polymer solar cells (PSC) were manufactured by depositing n-type polymers on Si/p-type substrate. And p-type polymers on the same area of Si/n-type substrate. The aluminium layer was deposition as an ohmic contact on Si by evaporation under the pressure of 3.5×10-6 Torre the upper electrode, copper metal, was deposited on the surface covered with the polymer film. The I-V characteristics were obtained using a light with a power of 100 mW/cm2. From I-V curves, the value of the filling factor-FF and power conversion efficiency- Ƞ were calculated. Then to improve the efficiency, four n-type polymers were chosen with the highest electrical conductivity. A solution of 99.9% purity of multi-walled carbon nanotubes (mWCNT) was added by depositing the mixture on a Si/p-type substrate using the spin-coating method. The results of final four cells after improving showed an increasing in the short-circuit current density between Jsc=(13.8-19.8) mA/cm2, the open-circuit voltage between Voc=(0.345 -0.370)V, the FF=(~38%) where the efficiency improved significantly and increased between ŋ =(2.6-4.48)%. The best PSC obtained gave a ŋ =1.07% before improvement, where after adding the carbon nanotube solution, it become about ŋ = 4.48%, that is, an increase of 4.18%. Therefore, the incorporation of carbon nanotubes into the organic conductive polymers can significantly improve the performance of the PSC.