Impact of <i>t</i>-butyl substitution in a rubrene emitter for solid state NIR-to-visible photon upconversion

Radiunas, Edvinas; Dapkevičius, Manvydas; Raišys, Steponas; Juršėnas, Saulius; Jozeliūnaitė, Augustina; Javorskis, Tomas; Šinkevičiūtė, Ugnė; Orentas, Edvinas; Kazlauskas, Karolis

doi:10.1039/d0cp00144a

Cited by 34 publications

(87 citation statements)

References 49 publications

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“…Interestingly, a lower UC signal is generally seen in regions with large crystalline rubrene agglomerates indicating that there may be a balance between 'too little' and 'too much' rubrene in efficient TTA-UC, and that packing of the upconverting molecules may play an important role in the UC process. [63] So far, we have confirmed that our one-step fabricated devices are active in TTA-UC. In the following, we seek to investigate how their properties differ from our previous bilayer device structure, and in how far the device structure influences the TTA-UC properties.…”

Section: Resultssupporting

confidence: 77%

One‐Step Fabrication of Perovskite‐Based Upconversion Devices

et al. 2020

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Device fabrication methods for applications in upconversion processes using perovskite thin films have suffered from reproducibility and scalability issues, which prevent the upscaling of this technology. In this contribution, we developed a perovskite‐based upconversion device approach where the triplet annihilator is added in situ to the antisolvent and investigated the effect of the device fabrication procedure on the properties of our device. By comparing the properties of a device based on our new fabrication approach with the existing bilayer procedure, we seek to shed light on the underlying optoelectronic processes influenced by the different fabrication methods, while further advancing possible device architectures for upconversion devices. Device characterization by optical methods, X‐ray diffraction and atomic force microscopy revealed that the in situ fabricated devices match the performance or even outcompete our previously developed bilayer devices while significantly simplifying the device fabrication. In particular, we find that the developed one‐step fabrication technique enables intercalation of the upconverting layer into the perovskite film prior to annealing, resulting in a larger interface thus, more efficient charge extraction.

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Section: Resultssupporting

confidence: 77%

One‐Step Fabrication of Perovskite‐Based Upconversion Devices

et al. 2020

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“…The fluorescence quantum yield Φ FL increased with the increase of the collector ratio and reached 84 % at 0.5 mol% of the collector (Figure 4a). This result indicates that the acceptor‐to‐collector FRET process outcompetes with the other deactivation processes, such as singlet fission [25,32] . The occurrence of FRET is also confirmed by the shortening of acceptor fluorescence lifetime (Figure S2).…”

Section: Resultsmentioning

confidence: 56%

“…This result indicates that the acceptor-to-collector FRET process outcompetes with the other deactivation processes, such as singlet fission. [25,32] The occurrence of FRET is also confirmed by the shortening of acceptor fluorescence lifetime ( Figure S2). The shape of fluorescence spectra changed with the increase in the collector ratio, and the original rubrene fluorescence mostly disappeared and the DBP fluorescence dominated at 0.5 mol% of collector DBP (Figure 4b).…”

Section: Understanding the Improved Tta-uc Efficiencymentioning

confidence: 62%

“…In addition to the enhanced fluorescence quantum yield, we found that the addition of collector DBP reduces the back energy transfer to the donor molecules. [32,34] The back energy transfer efficiency Φ BET was estimated from the following equation, Φ BET = 1-τ/τ 0 , where τ and τ 0 represent the fluorescence lifetime with/without the donor, respectively. The decay of Os(atpy)(tbbpy)Cl + /rubrene film became faster than that of rubrene film, indicating the presence of severe acceptor-to-donor back energy transfer (Figure 4c).…”

Section: Understanding the Improved Tta-uc Efficiencymentioning

confidence: 99%

“…Kazlauskas et al have also reported the increase of TTA-UC efficiency by the addition of DBP into spin-coated films of rubrene and t-butyl-substituted rubrene. [32] Our group reported the NIR-to-vis TTA-UC by employing the Os complex Os(atpy) (tbbpy)Cl + (atpy = tris(2-ethylhexyl)-[2,2' : 6',2''-terpyridine]-4,4',4''-tricarboxamide; tbbpy = 4,4'-di-tert-butyl-2,2''-bipyridine) that shows the SÀ T absorption over 900 nm. [28] The Os complex was molecularly doped in amorphous nanoparticles of rubrene by the simple aqueous reprecipitation method.…”

Section: Introductionmentioning

confidence: 99%

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Photon Upconverting Solid Films with Improved Efficiency for Endowing Perovskite Solar Cells with Near‐Infrared Sensitivity

et al. 2020

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Perovskite solar cells have emerged as the next-generation high-efficiency solar cell, but their absorption is mostly limited to the visible (vis) range. One possible solution is to integrate near-infrared (NIR)-to-vis photon upconversion (UC). Herein, we show the first example of endowing perovskite solar cells with NIR sensitivity by using solid films showing NIR-to-vis UC based on triplet-triplet annihilation (TTA). A high TTA-UC efficiency of 4.1 � 0.3 % at an excitation intensity of 125 W/cm 2 is achieved by sensitizing a rubrene (acceptor) triplet with an osmium (Os) complex donor having singlet-to-triplet (SÀ T) absorption in the NIR range, and by increasing the fluorescence quantum yield through energy harvesting to a highly fluorescent collector. In particular, our spectroscopic studies indicate that the upconverted acceptor singlet energy is almost selectively transferred to the collector rather than being quenched by the donor. By attaching the TTA-UC film behind a semi-transparent perovskite solar cell, a photocurrent generation is observed under excitation at 938 nm.

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Boost in Solid‐State Photon Upconversion Efficiency through Combined Approach of Melt‐Processing and Purification

2022

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Realization of efficient photon upconversion (UC) mediated by triplet–triplet annihilation (TTA) in a solid state is a great challenge, even though order of magnitude higher efficiencies are routinely reported in a solution/liquid state. To address this issue in a typical emitter/sensitizer UC system, a combined approach is introduced based on 1) thorough emitter purification for reduced exciton quenching and 2) UC film fabrication via melt‐processing for attaining large emitter concentrations with suppressed aggregation. Emitter purification via vacuum sublimation is shown to reduce the number of both singlet and triplet quenchers as confirmed by fluorescence and UC quantum yield measurements along with the respective transient measurements performed on nanosecond and millisecond time domains. Application of this approach to the benchmark TTA‐UC system DPA/PtOEP is demonstrated to yield a record‐high UC efficiency (=8 ± 1%, out of maximum 50%) achieved at 40 wt% of DPA homogeneously dispersed in the PMMA host. Importantly, such high efficiency is accomplished in large‐area amorphous films, the most preferred for practical applications, and featuring low UC threshold (=5 mW cm−2) that is close to the solar irradiance. The presented approach describes the guidelines for boosting UC efficiency in the solid state, and generally, is applicable to any conventional TTA‐UC system.

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Impact of t-butyl substitution in a rubrene emitter for solid state NIR-to-visible photon upconversion

Abstract: Enhanced TTA-UC performance of t-butyl-rubrene films as compared to that of unsubstituted-rubrene films is achieved due to suppressed singlet fission and non-radiative triplet quenching.

Cited by 34 publications

References 49 publications

One‐Step Fabrication of Perovskite‐Based Upconversion Devices

One‐Step Fabrication of Perovskite‐Based Upconversion Devices

Photon Upconverting Solid Films with Improved Efficiency for Endowing Perovskite Solar Cells with Near‐Infrared Sensitivity

Boost in Solid‐State Photon Upconversion Efficiency through Combined Approach of Melt‐Processing and Purification

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