Effects of HTL and ETL Thicknesses on the Performance of PQT-12/PCDTBT:PC61 BM/ZnO QDs Solar Cells

In this letter, floating film transfer method (FTM) based poly (3, 3”'dialkylquaterthiophene) (PQT-12) hole transfer layer (HTL) has been explored for the performance improvement of poly[N-9'-heptadecanyl-2,7-carbaZole-alt-5,5(4',7'-di-2-thienyl-2', 1', 3'-benZothiadiaZole)]:[6,6]-phenylC61butyric acid methyl ester (PCDTBT:PC61 BM) based bulk heterojunction (BHJ) solar cells. The BHJ is formed by sandwiching PCDTBT:PC61 BM between FTM coated PQT-12 HTL and spin-coated ZnO quantum dots (QDs) electron transport layer (ETL). The better phase matching of FTM deposited PQT-12 HTL to the PCDTBT:PC61 BM based blend polymeric active layer along with the visible absorption spectrum of the PQT-12 enhances the energy harvesting capability of the solar cell structure. The solar cell performance parameters such as the open circuit voltage (V
_OC
), short circuit current density (J
_SC
), fill factor (FF) and power conversion efficiency (PCE) are investigated for ~20 to 60 nm thin PQT-12 and ~20 to 35 nm thin ZnO films. The obtained V
_OC
, J
_SC
, FF, and PCE are 0.672 V, 10.42 mλ/cm
²
, 38%, and 2.66%, respectively for ~20 nm PQT-12 and ~35 nm ZnO QDs.