Simple electron donor molecules based on triphenylamine and carbazole derivatives

As the key properties of perovskite solar cells (PSCs), the hole extraction and transport capabilities of the hole transport material (HTM) affect the photovoltaic performance of PSCs to a considerable extent, while both capabilities can be adjusted by molecular planarity. Therefore, in this work, the molecular planarity of the HTM is systematically optimized to regulate the hole extraction and transport capabilities. Along with the improvement in planarity, the HTM′s HOMO level is increased, leading to the enhancement of hole extraction capability. Meanwhile, the hole transport capability can also be improved due to the intensification of molecular stacking during the film formation. As a result, the planar HTM achieves a relatively high efficiency of 18.48 %, which is higher than that of spiro‐OMeTAD. Accordingly, the molecular planarity presents an important impact on the photovoltaic performance of PSCs, providing us with a promising strategy for further optimization of efficient HTMs.

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“…The intermediate 3 was purchased from Energy Chemical Co., Ltd. The intermediate 4 was synthesized according to the published work [17] …”

Section: Methodsmentioning

confidence: 99%

Molecular Engineering of Star‐Shaped Indoline Hole Transport Materials: The Influence of Planarity on the Hole Extraction and Transport Processes

Yang

Guo

et al. 2022

Chemistry A European J

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“…41,42 Owing to the excellent redox activity of TPA-containing compounds, they are also used as organic electronic materials as well as luminescent probes, charge carriers, and fluorescence properties through radical cations. 43 The central N atom of sp 2 -hybridized TPA forming three N C co-planar bonds with three adjacent phenyl rings leave a valence lone pair of electrons on the N 2p z orbital. The delocalization of lone pair electron from ortho to meta position in phenyl rings of TPA unit results in propeller shape structures.…”

Section: Introductionmentioning

confidence: 99%

“…Alternatively, triphenylamine (TPA) and its derivatives consist of nonplanar, electrically conductive nature and potential hole‐transporting properties 41,42 . Owing to the excellent redox activity of TPA‐containing compounds, they are also used as organic electronic materials as well as luminescent probes, charge carriers, and fluorescence properties through radical cations 43 . The central N atom of sp 2 ‐hybridized TPA forming three NC co‐planar bonds with three adjacent phenyl rings leave a valence lone pair of electrons on the N 2p z orbital.…”

Section: Introductionmentioning

confidence: 99%

Highly stable bulk heterojunction organic solar cells based on asymmetric benzoselenadiazole‐oriented organic chromophores

Abdullah

Kim

Akhtar

et al. 2022

Intl J of Energy Research

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Summary A new asymmetrically designed D‐A‐D organic chromophore 4‐(7‐(5′‐hexyl‐[2,2′‐bithiophen]‐5‐yl)benzo[c][1,2,5]selenadiazol‐4‐yl)‐N,N‐diphenylaniline (RSeT) with benzoselenadiazole acceptor unit has been synthesized using two different electron donor materials of triphenylamine (TPA) and n‐hexyl bithiophene unit. Attachment of nonplanar electron‐donating TPA unit subsequently heightened the optoelectronic properties and altered the solubility in organic solvents. RSeT of the optical bandgap of ~1.95 eV with the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of −5.31 and −3.36 eV was applied as an electron donor material for stable bulk heterojunction organic solar cells. In this work, two different buffer layers of poly (3, 4‐ethylenedioxythiophene):polystyrene sulfonate acid (PEDOT:PSS) and compact titanium oxide (c‐TiO2) were used and their influences on the device performance were investigated. Buffer layer of c‐TiO2 with RSeT:PC61BM (1:3, w/w) active layer achieved a high open‐circuit voltage (Voc) of ~0.985 V, short‐circuit current density (Jsc) of ~11.26 mA/cm2 and improved fill factor of ~0.62 which resulted in a high power conversion efficiency (PCE) of ~6.88%. After 30 days, interestingly, RSeT:PC61BM (1:3, w/w) devices with a c‐TiO2 buffer layer demonstrated good stability with the PCE value remaining at 85% of its initial value.

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“…18 When conjugated with strong donor groups, e.g., triphenylamine (TPE) derivatives, this system can undergo strong intramolecular charge transfer (ICT), which further facilitates a bathochromic shift of the emission. 19,20 However, the precise role ICT plays in forming an aggregate and how it enhances emission remain unclear, particularly in the solution phase.…”

Section: ■ Introductionmentioning

confidence: 99%

Ultrafast Aggregation-Induced Tunable Emission Enhancement in a Benzothiadiazole-Based Fluorescent Metal–Organic Framework Linker

et al. 2021

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Aggregation-induced emission enhancement (AIEE) is a process recently exploited in solid-state materials and organic luminophores, and it is explained by tight-molecular packaging. However, solution-phase AIEE and its formation mechanism have not been widely explored. This work investigated AIEE phenomena in two donor–acceptor–donor-type benzodiazole-based molecules (the organic building block in metal–organic frameworks) with an acetylene and phenyl π-conjugated backbone tapered with a carboxylic acid group at either end. This was done using time-resolved electronic and vibrational spectroscopy in conjunction with time-dependent density functional theory (TD-DFT) calculations. Fluorescence up-conversion spectroscopy and time-correlated single-photon counting conclusively showed an intramolecular charge transfer-driven aggregate emission enhancement. This is shown by a red spectral shift of the emission spectra as well as an increase in the fluorescence lifetime from 746 ps at 1.0 × 10–11 to 2.48 ns at 2.0 × 10–3 M. The TD-DFT calculations showed that a restricted intramolecular rotation mechanism is responsible for the enhanced emission. The femtosecond infrared (IR) transient absorption results directly revealed the structural dynamics of aggregate formation, as evident from the evolution of the CC vibrational marker mode of the acetylene unit upon photoexcitation. Moreover, the IR data clearly indicated that the aggregation process occurred over a time scale of 10 ps, which is consistent with the fluorescence up-conversion results. Interestingly, time-resolved results and DFT calculations clearly demonstrated that both acetylene bonds and the sulfur atom are the key requirements to achieve such a controllable aggregation-induced fluorescence enhancement. The finding of the work not only shows how slight changes in the chemical structure of fluorescent chromophores could make a tremendous change in their optical behavior but also prompts a surge of research into a profound understanding of the mechanistic origins of this phenomenon. This may lead to the discovery of new chemical strategies that aim to synthesize novel chromophores with excellent optical properties for light-harvesting applications.

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Simple electron donor molecules based on triphenylamine and carbazole derivatives

Cited by 30 publications

References 42 publications

Molecular Engineering of Star‐Shaped Indoline Hole Transport Materials: The Influence of Planarity on the Hole Extraction and Transport Processes

Molecular Engineering of Star‐Shaped Indoline Hole Transport Materials: The Influence of Planarity on the Hole Extraction and Transport Processes

Highly stable bulk heterojunction organic solar cells based on asymmetric benzoselenadiazole‐oriented organic chromophores

Ultrafast Aggregation-Induced Tunable Emission Enhancement in a Benzothiadiazole-Based Fluorescent Metal–Organic Framework Linker

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