Structure dependent photostability of ITIC and ITIC-4F

Ciammaruchi, Laura; Zapata‐Arteaga, Osnat; Gutiérrez‐Fernández, Edgar; Martı́n, Jaime San; Campoy‐Quiles, Mariano

doi:10.1039/d0ma00458h

Cited by 29 publications

(41 citation statements)

References 72 publications

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“… 54 Besides performance, annealing gradients were recently employed to assess the relationship between post-thermal treatment and photostability of state-of-the art OPV materials. 74 …”

Section: High-throughput Experimentation Workflows In Opvmentioning

confidence: 99%

Accelerating organic solar cell material's discovery: high-throughput screening and big data

Rodríguez‐Martínez

Pascual-San-José

Campoy‐Quiles

2021

Energy Environ. Sci.

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“… 54 Besides performance, annealing gradients were recently employed to assess the relationship between post-thermal treatment and photostability of state-of-the art OPV materials. 74 …”

Section: High-throughput Experimentation Workflows In Opvmentioning

confidence: 99%

Accelerating organic solar cell material's discovery: high-throughput screening and big data

Rodríguez‐Martínez

Pascual-San-José

Campoy‐Quiles

2021

Energy Environ. Sci.

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“…[18] However, the increase in the degree of crystallinity achieved by annealing the devices at temperatures above the T g of ITIC was detrimental, drastically reducing the PCE. [12c] To rationalize the above results, Yu et al [12c] and Ciammaruchi et al [19] have suggested that ITIC is able to crystallize into different polymorphs, i.e., a low-temperature polymorph that develops via diffusion limited crystallization at temperatures below T g and a high-temperature polymorph that develops by regular cold crystallization at temperatures above the T g .…”

Section: Introductionmentioning

confidence: 99%

“…[ 12c ] and Ciammaruchi et al. [ 19 ] have suggested that ITIC is able to crystallize into different polymorphs, i.e., a low‐temperature polymorph that develops via diffusion limited crystallization at temperatures below T g and a high‐temperature polymorph that develops by regular cold crystallization at temperatures above the T g .…”

Section: Introductionmentioning

confidence: 99%

Polymorphism in Non‐Fullerene Acceptors Based on Indacenodithienothiophene

Marina

Scaccabarozzi

Gutiérrez‐Fernández

et al. 2021

Adv Funct Materials

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Organic solar cells incorporating non-fullerene acceptors (NFAs) have reached remarkable power conversion efficiencies of over 18%. Unlike fullerene derivatives, NFAs tend to crystallize from solutions, resulting in bulk heterojunctions that include a crystalline acceptor phase. This must be considered in any morphology-function models. Here, it is confirmed that high-performing solution-processed indacenodithienothiophene-based NFAs, i.e., ITIC and its derivatives ITIC-M, ITIC-2F, and ITIC-Th, exhibit at least two crystalline forms. In addition to highly ordered polymorphs that form at high temperatures, NFAs arrange into a low-temperature metastable phase that is readily promoted via solution processing and leads to the highest device efficiencies. Intriguingly, the low-temperature forms seem to feature a continuous network that favors charge transport despite of a poorly order along the π-π stacking direction. As the optical absorption of the structurally more disordered low-temperature phase can surpass that of the more ordered polymorphs while displaying comparable-or even higher-charge transport properties, it is argued that such a packing structure is an important feature for reaching highest device efficiencies, thus, providing guidelines for future materials design and crystal engineering activities.

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“…Among these, IT-4F showed the highest photoreactivity and complete degradation within hours (Figure 4 and Figure S8). Interestingly, its non-fluorinated congener (ITIC) showed a slower photoconversion which is opposite to what is expected for photooxidation (and observed in laser-induced photodegradations of IT-4F and ITIC [35] ). A slightly higher activation energy for the electrocyclization of ITIC was predicted by DFT (Table 2 and Table S3) and is likely due to lower LUMO wavefunction density on the dicyanomethylene moiety of the non-fluorinated acceptor, leading to weaker HOMO-LUMO interaction in the transition state.…”

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confidence: 63%

Mechanism of the Photodegradation of A‐D‐A Acceptors for Organic Photovoltaics**

et al. 2021

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Herein, we elucidate the photodegradation pathway of A-D-A-type non-fullerene acceptors for organic photovoltaics. Using IT-4F as a benchmark example, we isolated the photoproducts and proved them isomers of IT-4F formed by a 6-e electrocyclic reaction between the dicyanomethylene unit and the thiophene ring, followed by a 1,5-sigmatropic hydride shift. This photoisomerization was accelerated under inert conditions, as explained by DFT calculations predicting a triplet-mediated reaction path (quenchable by oxygen). Adding controlled amounts of the photoproduct P1 to PM6:IT-4F bulk heterojunction cells led to a progressive decrease in photocurrent and fill factor attributed to its poor absorption and charge transport properties. The reaction is a general photodegradation pathway for a series of A-D-A molecules with 1,1-dicyanomethylene-3-indanone termini, and its rate varies with the structure of the donor and acceptor moiety.

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Structure dependent photostability of ITIC and ITIC-4F

Abstract: ITIC photostability is markedly dependent on the specific polymorph phase and end-group decoration. Fluorination grants stronger chemical stability upon degradation.

Cited by 29 publications

References 72 publications

Accelerating organic solar cell material's discovery: high-throughput screening and big data

Accelerating organic solar cell material's discovery: high-throughput screening and big data

Polymorphism in Non‐Fullerene Acceptors Based on Indacenodithienothiophene

Mechanism of the Photodegradation of A‐D‐A Acceptors for Organic Photovoltaics**

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