Effects of HTL and ETL Thicknesses on the Performance of PQT-12/PCDTBT:PC<sub>61</sub>BM/ZnO QDs Solar Cells
Amit Kumar, Deepak Kumar Jarwal, Ashwini Kumar Mishra, Smrity Ratan, Chandan Kumar, Rishibrind Kumar Upadhyay, Bratindranath Mukherjee, Satyabrata Jit
Abstract
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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> ), short circuit current density (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> ), 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> , J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> , FF, and PCE are 0.672 V, 10.42 mλ/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 38%, and 2.66%, respectively for ~20 nm PQT-12 and ~35 nm ZnO QDs.