New design and optimization of half-tandem quantum dot solar cell: Over 30% power conversion efficiency using nanostructure oriented core-shell

Abstract

We achieve 30.64% power conversion efficiency (PCE) by comprehensive design and optimization of half-tandem quantum dot (QD) solar cell using nanostructure-oriented core-shell to improve open circuit voltage (Voc) in QD solar cell (QDSC) for first time. In this study, we have used coupling of optical and electrical equations to calculate solar cell parameters. The aim of this study was to optimize the reference structure including PbS quantum dots (PbS-QDs) treated with tetrabutylammonium iodide (PbS-TBAI), Magnesium Zinc Oxide (MgZnO) and PbS ethanedithiol (PbS-EDT) for active layer (AL), electron transport layer (ETL) and hole transport layer (HTL) respectively. At first, the structure was enhanced into half-tandem solar cell by adding Molybdenum Ditelluride (MoTe2) as the second absorber layer to cover the infrared region. Furthermore, the structure was optimized in four steps: (i) adding a Spiro-OMeTAD layer to reduce the series resistance (Rs) and prevent electrons from entering aluminum metal contact, (ii) adding a core-shell (CFTS – SnS) nanostructure, (iii) optimizing ETL, and (iv) investigating the effect of core-shell nanostructure angle. As a final result, the values of short circuit current (Jsc), Voc, PCE, fill factor (FF) and series resistance were obtained 25.25 mA/cm2, 1.49 V, 30.64 %, 0.78 and 2.8 Ω/cm2, respectively.