Efficient Charge Separation Enabled by N-Doped Graphene Quantum Dots and PCDTBT for a High-Performance Silicon Nanowire Solar Cell

Maity, Debanjan and Kolay, Ankita and Deepa, Melepurath (2021) Efficient Charge Separation Enabled by N-Doped Graphene Quantum Dots and PCDTBT for a High-Performance Silicon Nanowire Solar Cell. ACS Applied Energy Materials, 4 (6). pp. 5625-5638. ISSN 2574-0962

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Abstract

Light absorption by n-silicon nanowires (SiNWs) grown by a chemical etching method is augmented by tethering photoresponsive and highly luminescent nitrogen-doped graphene quantum dots (N-GQDs) and poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) to a SiNW array. The resultant N-GQDs@PCDTBT@SiNW photoanode affords a wide, continuous, and intense absorption band spanning from ∼350 to 1200 nm wavelength range, enabling maximum light uptake, with a work function of ∼4.74 eV, deep enough to not serve as a charge-trapping state. Under illumination, efficient charge separation in this ternary composite is ensured by the p-type semiconducting nature of N-GQDs with a shallow valence band (VB) that allows for rapid hole extraction from the VBs of SiNW and PCDTBT and their rapid relay to the bromide ions in the electrolyte. This is simultaneously accompanied by fast, excited electron injection from N-GQDs and PCDTBT to the SiNW via a cascade process, thus minimizing back electron transfer to the tribromide ions. When the N-GQDs@PCDTBT@SiNW photoanode is coupled with a highly electrocatalytic and electrically conductive multiwalled carbon nanotube (MWCNT)@C-fabric counter electrode and a bromine/bromide electrolyte, a power conversion efficiency of 13.18% is achieved for this liquid junction solar cell, which is significantly enhanced compared to that of the SiNW/HBr,Br2/C-fabric cell (4.37%). The roles of N-GQDs, PCDTBT, and MWCNTs are independently quantified to explain the observed solar cell performance.

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IITH Creators:

IITH Creators	ORCiD
Kolay, Ankita	UNSPECIFIED
M, Deepa	UNSPECIFIED

Item Type:

Article

Uncontrolled Keywords:

efficiency; graphene; nanowires; silicon; solar;Back electron transfer; Charge separations; Counter electrodes; Electrically conductive; Nitrogen doped graphene; Power conversion efficiencies; Solar cell performance; Ternary composites;Charge trapping; Conversion efficiency; Doping (additives); Electrolytes; Electron transport properties; Etching; Graphene; Graphene quantum dots; Ions; Light absorption; Multiwalled carbon nanotubes (MWCN); Nanocrystals; Nanowires; Semiconductor quantum dots; Silicon; Silicon compounds

Subjects:

Chemistry

Divisions:

Department of Chemistry

Depositing User:

. LibTrainee 2021

Date Deposited:

05 Jul 2021 09:04

Last Modified:

14 Mar 2022 06:44

URI:

http://raiithold.iith.ac.in/id/eprint/8105