Azulene Bridged π‐Distorted Chromophores: The Influence of Structural Symmetry on Optoelectrochemical and Photovoltaic Parameters. Issue 10 (14th October 2021)

• Record Type: Journal Article
• Authors: Raheem, Abbasriyaludeen Abdul; Murugan, Palanichamy; Shanmugam, Ramasamy; Praveen, Chandrasekar
• Is Part Of: ChemPlusChem. Volume 86:Issue 10(2021)
• Page Start: 1451
• Page End: 1460
• Publication Date: 2021-10-14
• Subjects: azulenes -- nonfullerene acceptors -- photovoltaic devices -- semiconductors -- twisted chromophores; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/cplu.202100392
• Languages: English
• ISSNs: 2192-6506

Abstract

Abstract: Conjugated chromophores possessing π‐twisted functionality such as tetracyanobutadiene (TCBD) have emerged as promising active layer materials for organic photovoltaics (OPVs). In this study, we disclose the synthesis of two azulenyl chromophores containing one and two TCBD groups. The symmetrical and unsymmetrical structural characteristics of these molecules inflict dissimilar optoelectronic and electrochemical properties. Based on molar absorptivity, aggregation behavior, HOMO‐LUMO energies and other quantum chemical parameters, the symmetrical molecule (TATC2) appears to be a better non‐fullerene acceptor (NFA) compared to its unsymmetrical counterpart (TATC1). For instance, higher absorptivity and deeper HOMO‐LUMO levels for TATC2 (23950 M −1 cm −1 ; −6.01 eV/−3.86 eV) over TATC1 (12200 M 1 cm −1 ; −5.46 eV/−3.64 eV) was observed. Validating this structure‐property relationship on solar cell prototypes exhibited higher photovoltaic parameters ( V OC =0.54 V, FF=0.48, J SC =6.42 mA/cm 2 ) for TATC2 than TATC1 ( V OC =0.47 V, FF=0.38, J SC =5.77 mA/cm 2 ). Though the device parameters are not high, this work uncovers the intrinsic properties of azulene‐tethered twisted chromophores as potential π‐semiconductor choice for NFA solar cells. In particular, this report explores the utility of azulene‐based π‐twisted semiconductors as acceptor material for OPVs with cell efficiencies of 1.70 and 1.04 % for TATC2 and TATC1 respectively. Abstract : The inclusion of twisted π‐groups like tetracyanobutadiene (TCBD) on dithienyl‐azulene and the impact of such functionalization on thermochemical, optoelectronics, electrochemical as well as photovoltaic properties were studied. Comparison of structural manipulation by incorporating one TCBD (unsymmetric) against two TCBD groups (symmetric) led to better molecular parameters for symmetric chromophore to fulfill non‐fullerene acceptor characteristics.