Cyclopentadithiophene-based co-oligomers for solution-processed organic solar cells

Abstract

a b s t r a c tA new family of low band-gap co-oligomers based on 4H-cyclopenta[2,1-b:3,4-b']dithiophene (CPDT) and thieno[3,2-b]thiophene (TT) units as central electron-donor cores has been synthesized and characterized for use as electron-donor materials in solution-processed bulk-heterojunction organic solar cells. An in-depth study into the role played by the hexyl chains linked to the thienylenevinylene-based p-bridge has been carried out. Power conversion efficiencies (PCE) of up to 4% and external quantum efficiencies as high as 50% have been achieved. Experiments carried out after solvent vapour annealing (SVA) as a post-treatment led to a doubling of the fill factor (FF) and PCE.

Designing Well-Organized Donor-Bridge-Acceptor Conjugated Systems Based on Cyclopentadithiophene as Donors in Bulk Heterojunction Organic Solar Cells: DFT-Based Modeling and Calculations

“…In fact, these maximum wavelengths are generated mainly from HOMOs to LUMOs electronic transitions of ground to first excited state (S 0 → S 1 ) of electrons associated with high oscillator strength (f) values. Where, the pronounced absorption peaks are generated by π → π* electronic transitions from the electron donating CPDT moieties to theelectron acceptor BT or DPP moieties [57]. The simulated absorption spectrum of P-CPDTBT3 is in convenient agreement with the experimental results reported in ref.…”

Searching for Models Exhibiting High Circularly Polarized Luminescence: Electroactive Inherently Chiral Oligothiophenes

“…[9] BT 2 -T 4 satisfies the mentioned structural requirements, and, in fact, it exhibits good CPL activity also as monomer, [2c] suggesting that inherently chiral oligothiophenes could be exploited in the field of photonics. Fused-ring derivatives of heteroaromatic compounds are today very popular buildingb locks, because they lead to more extendedc onjugation in the ground state, more planar molecular geometry andm ore rigid structures, with decreased HOMO-LUMO separation and increased charge mobility.I n particular, we focusedo ur attentiono nt he 4H-cyclopenta[2,1-b3:4b']dithiophene( CPDT) [10] and on the dithieno[3,3-b:2',3'd]pyrrole (DTP) [11] ,b otho fw hich have been largely employed as monomersf or the preparation of materialsw idely used for preparing variousd evices, like OLEDs, FETs, and OPVs (OLED = organic light emitting device;F ET = field effect transistor; OPV = organic photo-voltaics). Fused-ring derivatives of heteroaromatic compounds are today very popular buildingb locks, because they lead to more extendedc onjugation in the ground state, more planar molecular geometry andm ore rigid structures, with decreased HOMO-LUMO separation and increased charge mobility.I n particular, we focusedo ur attentiono nt he 4H-cyclopenta[2,1-b3:4b']dithiophene( CPDT) [10] and on the dithieno[3,3-b:2',3'd]pyrrole (DTP) [11] ,b otho fw hich have been largely employed as monomersf or the preparation of materialsw idely used for preparing variousd evices, like OLEDs, FETs, and OPVs (OLED = organic light emitting device;F ET = field effect transistor; OPV = organic photo-voltaics).…”

“…In this work, we reporto nt he CPL spectra of the antipodes of two new inherently chiral monomers based on the same atropisomeric scaffold, but functionalized with fused ring bithiophene derivatives. Fused-ring derivatives of heteroaromatic compounds are today very popular buildingb locks, because they lead to more extendedc onjugation in the ground state, more planar molecular geometry andm ore rigid structures, with decreased HOMO-LUMO separation and increased charge mobility.I n particular, we focusedo ur attentiono nt he 4H-cyclopenta[2,1-b3:4b']dithiophene( CPDT) [10] and on the dithieno[3,3-b:2',3'd]pyrrole (DTP) [11] ,b otho fw hich have been largely employed as monomersf or the preparation of materialsw idely used for preparing variousd evices, like OLEDs, FETs, and OPVs (OLED = organic light emitting device;F ET = field effect transistor; OPV = organic photo-voltaics). In principle, these heterocycles should allow us to obtain materials characterizedb ym ore extended conjugation and easier processability than those obtained from BT 2 -T 4 ,d ue to the possibility to functionalize them with lypophilic alkyl chains.…”

Conjugated polymers and small molecules containing the thiophene–vinylene–thiophene (TVT) unit for organic photovoltaic applications

“…Of note is that the G21-based devices present a high V OC of 1.06 V due to their low-lying HOMO level. 88 In short, in these A-D-A type donor molecules, whether TVT is the central electron-donating unit or the bridge between D and A units, the designed molecules performed very poorly in the fullerene system, mainly because both J SC and FF of devices are quite low. The highest PCE is close to 5%, and most of them present a PCE of less than 3%, which might originate from the poor molecular packing caused by the steric hindrance of TVT in the main chain.…”

“…Of note is that the G21 -based devices present a high V OC of 1.06 V due to their low-lying HOMO level. 88…”