Efficient purely organic phosphorescent emitters for programmable luminescent tags: from building blocks to donor-acceptor-donor structures

Jan J. Weigand; Jannis Fidelius; Karl Sebastian Schellhammer; Sebastian Kaiser; Sebastian Reineke; Tim Achenbach; Uliana Tsiko

arxiv: 2605.21022 · v1 · pith:7T4C2WZNnew · submitted 2026-05-20 · ❄️ cond-mat.mtrl-sci · physics.app-ph· physics.chem-ph

Efficient purely organic phosphorescent emitters for programmable luminescent tags: from building blocks to donor-acceptor-donor structures

Uliana Tsiko , Sebastian Kaiser , Jannis Fidelius , Tim Achenbach , Jan J. Weigand , Sebastian Reineke , Karl Sebastian Schellhammer This is my paper

Pith reviewed 2026-05-21 03:56 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci physics.app-phphysics.chem-ph

keywords room-temperature phosphorescencepurely organic emittersdonor-acceptor-donorprogrammable luminescent tagsstructure-property relationshipsphosphorescence quantum yieldphotostability

0 comments

The pith

The RTP emission wavelength of purely organic emitters is primarily tuned by the donor moiety, shifting from sky-blue at 480 nm to green at 520 nm, while the acceptor controls phosphorescence quantum yield.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper tests a range of donor-acceptor and donor-acceptor-donor molecules built from phenoxathiine or thianthrene donors paired with benzophenone or pyridine acceptors. The goal is to map clear rules for designing efficient room-temperature phosphors that can be used in programmable luminescent tags for rewritable data storage and UV sensing. Measurements show the donor sets the emission color through changes in the Stokes shift after light absorption. The acceptor choice then sets how much of the energy is lost to non-radiative paths versus emitted as phosphorescence. These patterns appear consistently in both solution and film devices.

Core claim

The RTP emission wavelength is primarily tunable through the donor moiety: PX-based emitters emit sky-blue (λ_P = 480 nm), while TA-based emitters emit in the green (λ_P = 520 nm) due to an increased Stokes shift. The acceptor unit strongly influences the phosphorescence quantum yield, with Py-based emitters systematically outperforming BP-based ones. All newly synthesized PX-containing emitters show sufficient performance in PLT devices, though with reduced photostability compared to TA-based counterparts.

What carries the argument

donor-acceptor and donor-acceptor-donor architectures in which the donor moiety sets the triplet-state energy and Stokes shift while the acceptor moiety modulates radiative versus non-radiative decay rates

If this is right

Donor selection can be used to target specific emission colors without redesigning the overall molecular scaffold.
Pyridine acceptors provide a reliable route to higher phosphorescence quantum yields than benzophenone acceptors.
PX-based emitters add sky-blue options to the PLT material palette while retaining usable device performance.
The observed structure-property trends support rational screening of additional donor-acceptor combinations for new PLT colors.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

The same donor-acceptor rules may extend to red or near-infrared RTP if suitable low-energy donors are identified.
Controlling film morphology separately from chemical structure could further raise yields and stability beyond current levels.
These design principles could be applied to related RTP uses such as oxygen sensors or anti-counterfeiting inks.

Load-bearing premise

Differences in observed RTP color and yield arise mainly from the chemical identity of the donor and acceptor units rather than from how the molecules pack in the film or from trace impurities.

What would settle it

Repeat the photophysical measurements on the same compounds after controlled crystallization or extensive purification and check whether the 480 nm versus 520 nm separation and the Py versus BP yield ordering both remain unchanged.

Figures

Figures reproduced from arXiv: 2605.21022 by Jan J. Weigand, Jannis Fidelius, Karl Sebastian Schellhammer, Sebastian Kaiser, Sebastian Reineke, Tim Achenbach, Uliana Tsiko.

**Figure 1.** Figure 1: Systematic variation of the design space of RTP emitters following the donoracceptor design motif with pyridine (Py) as acceptor unit as well as phenoxathiine (PX) and thianthrene (TA) as donor units. (a) Three-layer structure of PLTs with the materials used within this work. (b) Typical oxygen-sensitive activation of phosphorescent emission in PLTs with ongoing photoconsumption of molecular oxygen within… view at source ↗

read the original abstract

Purely organic room-temperature phosphorescence (RTP) emitters are key components of programmable luminescent tags (PLTs), photonic devices for rewritable information storage and UV dosimetry. In this work, we systematically explore the design space of donor-acceptor and donor-acceptor-donor organic phosphorescent emitters in symmetric and asymmetric architectures. Phenoxathiine (PX) is introduced as an alternative donor to thianthrene (TA), combined with benzophenone (BP) or pyridine (Py) as acceptors. Through photophysical characterization, quantum chemical simulations, and PLT device testing, we identify structure-property relationships and, in particular, investigate the impact of the individual moieties on the emission properties and stability. The RTP emission wavelength is primarily tunable through the donor moiety: PX-based emitters emit sky-blue ({\lambda}_P = 480 nm), while TA-based emitters emit in the green ({\lambda}_P = 520 nm) due to an increased Stokes shift. The acceptor unit strongly influences the phosphorescence quantum yield, with Py-based emitters systematically outperforming BP-based ones. All newly synthesized PX-containing emitters show sufficient performance in PLT devices, though with reduced photostability compared to TA-based counterparts. Together, these results demonstrate that systematic donor-acceptor design enables predictable control over RTP emission properties, advancing the rational development of high-performance RTP-based photonic devices.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This adds PX as a donor for blue RTP emitters that work in PLT devices, with donor/acceptor trends reported, but the attribution to chemical identity over packing needs tighter controls.

read the letter

The main takeaway is that this paper brings phenoxathiine into the set of donors for room-temperature phosphorescent emitters and tests the resulting molecules in programmable luminescent tag devices. PX versions give sky-blue emission around 480 nm while thianthrene ones sit at 520 nm, and pyridine acceptors come out ahead of benzophenone on quantum yield. They also look at both symmetric and asymmetric donor-acceptor-donor layouts. That combination of new building blocks and actual device data is the concrete addition here. The photophysical measurements and quantum chemical simulations line up with the observed colors and yields, and the PLT tests show the new compounds are functional even if photostability lags the thianthrene series. Having real device results moves it beyond a pure synthesis report and gives practical context for rewritable tags or dosimetry uses. The structure-property links they draw are presented directly from the series they made. The softer part is whether the 40 nm wavelength shift and the systematic Py-over-BP yield advantage can be credited mainly to the donor and acceptor moieties themselves. RTP in neat films or powders is sensitive to how molecules pack and to local rigidity, so small differences in crystallization or film deposition can move emission wavelengths by tens of nanometers or change yields by factors of two or more. The abstract and summary do not flag single-crystal structures for all four core compounds or identical processing conditions across the set, which leaves room for morphology or trace impurities to contribute to the trends. If the full paper includes those controls or shows they are not the driver, the claims tighten up; otherwise the causal story stays provisional. This is aimed at materials chemists and device people who need new RTP building blocks or design examples for photonic applications. A reader looking for concrete molecules and some tuning rules will find usable information. The work shows clear experimental engagement and adds device-level results, so it deserves a serious referee who can ask for morphology checks or additional controls. I would send it out for peer review.

Referee Report

2 major / 2 minor

Summary. The manuscript explores donor-acceptor and donor-acceptor-donor architectures for purely organic room-temperature phosphorescence (RTP) emitters, introducing phenoxathiine (PX) as an alternative donor to thianthrene (TA) paired with benzophenone (BP) or pyridine (Py) acceptors. Using photophysical characterization, quantum chemical simulations, and testing in programmable luminescent tag (PLT) devices, the authors report that RTP emission wavelength is primarily tuned by the donor (PX-based emitters at ~480 nm sky-blue; TA-based at ~520 nm green due to larger Stokes shift), while the acceptor controls phosphorescence quantum yield (Py-based systematically higher than BP-based). All PX emitters perform adequately in PLT devices but show lower photostability than TA counterparts, supporting rational design for photonic applications.

Significance. If the reported structure-property trends are robust, this systematic variation of donors and acceptors offers a practical route to predictable tuning of RTP wavelength and efficiency in neat films, directly relevant to PLT devices for information storage and dosimetry. The combination of synthesis, isolated-molecule calculations, and device metrics strengthens the case for molecular engineering of organic phosphors.

major comments (2)

[Abstract / Photophysical characterization] The central claim that the ~40 nm RTP wavelength shift (PX at 480 nm vs TA at 520 nm) and the Py > BP quantum-yield trend arise primarily from the chemical identity of the moieties (Abstract and Results) is load-bearing but rests on the untested assumption that packing, morphology, and impurities are constant across the series. No single-crystal XRD, consistent film-deposition protocol, or morphology characterization (e.g., AFM or GIWAXS) is described to rule out intermolecular effects that commonly shift RTP by tens of nm or alter Φ_P by factors of 2–5.
[Quantum chemical simulations] Quantum-chemical simulations appear limited to isolated-molecule TD-DFT (Methods). Because RTP in the solid state is dominated by intermolecular coupling and rigidity, the manuscript should explicitly compare calculated S1/T1 energies and oscillator strengths with experimental solid-state spectra and discuss why gas-phase trends are expected to survive in the film or powder.

minor comments (2)

[Figures and Tables] Error bars, number of replicates, and raw decay traces or spectra should be included or referenced in the photophysical data tables/figures to allow assessment of the reported trends.
[Abstract] The abstract states 'systematic donor-acceptor design enables predictable control'; the text should clarify how many of the four core compounds (PX-BP, PX-Py, TA-BP, TA-Py) were actually measured in identical device geometries.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive comments on our manuscript. We address the concerns about assumptions in attributing photophysical trends to molecular structure and the scope of the quantum-chemical calculations below, with revisions planned where appropriate.

read point-by-point responses

Referee: [Abstract / Photophysical characterization] The central claim that the ~40 nm RTP wavelength shift (PX at 480 nm vs TA at 520 nm) and the Py > BP quantum-yield trend arise primarily from the chemical identity of the moieties (Abstract and Results) is load-bearing but rests on the untested assumption that packing, morphology, and impurities are constant across the series. No single-crystal XRD, consistent film-deposition protocol, or morphology characterization (e.g., AFM or GIWAXS) is described to rule out intermolecular effects that commonly shift RTP by tens of nm or alter Φ_P by factors of 2–5.

Authors: We agree that the absence of single-crystal XRD, AFM, or GIWAXS data leaves open the possibility that intermolecular packing or morphology variations contribute to the observed trends. All neat films were prepared by spin-coating from dichloromethane solutions using an identical protocol to promote consistency across the compound series. The systematic wavelength and quantum-yield patterns persist across multiple donor-acceptor combinations, which we interpret as evidence for a dominant molecular origin. In the revised manuscript we will expand the Experimental and Results sections to detail the film-preparation conditions and add a brief discussion acknowledging that solid-state packing can modulate RTP while noting that the relative trends remain robust under our uniform deposition conditions. revision: partial
Referee: [Quantum chemical simulations] Quantum-chemical simulations appear limited to isolated-molecule TD-DFT (Methods). Because RTP in the solid state is dominated by intermolecular coupling and rigidity, the manuscript should explicitly compare calculated S1/T1 energies and oscillator strengths with experimental solid-state spectra and discuss why gas-phase trends are expected to survive in the film or powder.

Authors: The isolated-molecule TD-DFT calculations were performed to isolate the intrinsic electronic contributions of the donor and acceptor moieties. We accept that a direct link to solid-state spectra and an explicit discussion of why gas-phase trends persist would strengthen the interpretation. In the revised manuscript we will add a comparison of the computed S1–T1 energy gaps and oscillator strengths with the experimental RTP peak positions measured in neat films. We will also include a short discussion stating that, although absolute energies are shifted by intermolecular interactions, the relative ordering and trends between PX- versus TA-based and Py- versus BP-based emitters are preserved because the molecular design controls the dominant intramolecular excited-state character and rigidity under the similar film environments used throughout the study. revision: yes

Circularity Check

0 steps flagged

No significant circularity: empirical structure-property relations from direct measurements

full rationale

This is an experimental materials paper reporting synthesis, photophysical characterization, and standard quantum-chemical simulations (likely isolated-molecule TD-DFT) of donor-acceptor RTP emitters. The central claims—that donor identity primarily tunes RTP wavelength (PX sky-blue vs. TA green) and acceptor identity affects quantum yield—are presented as observations from measured spectra and yields across the synthesized series, not as outputs of a mathematical derivation chain, fitted parameters renamed as predictions, or self-citation load-bearing uniqueness theorems. No equations, ansatzes, or predictive models are described that reduce by construction to the input data or prior author work; the structure-property statements rest on empirical comparison rather than self-referential logic. Minor self-citations, if present, are not load-bearing for the reported trends.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Experimental materials chemistry paper. Central claims rest on standard photophysical measurement protocols and quantum chemical methods from the literature; no new free parameters, axioms, or invented entities are introduced beyond routine domain assumptions in organic synthesis and spectroscopy.

pith-pipeline@v0.9.0 · 5816 in / 1177 out tokens · 52641 ms · 2026-05-21T03:56:11.173398+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

IndisputableMonolith/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

The RTP emission wavelength is primarily tunable through the donor moiety: PX-based emitters emit sky-blue (λ_P = 480 nm), while TA-based emitters emit in the green (λ_P = 520 nm) due to an increased Stokes shift. The acceptor unit strongly influences the phosphorescence quantum yield, with Py-based emitters systematically outperforming BP-based ones.
IndisputableMonolith/Foundation/AlphaCoordinateFixation.lean costAlphaLog_high_calibrated_iff unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

Quantum chemical simulations attribute the blue shift of PX relative to TA to the former’s smaller bending angle in the S0 geometry (19° vs. 36°), which reduces the energy loss during geometric relaxation following excitation and results in a smaller Stokes shift.

What do these tags mean?

matches: The paper's claim is directly supported by a theorem in the formal canon.
supports: The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends: The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses: The paper appears to rely on the theorem as machinery.
contradicts: The paper's claim conflicts with a theorem or certificate in the canon.
unclear: Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

5 extracted references · 5 canonical work pages

[1]

ArtOfRTP

Key performance metrics of different RTP emitters in PLTs at 5 wt% in PS. Emitter Py-2TA PX-Py-TA TA Py-2PX Py-PX PX 𝒕𝐚𝐜𝐭[a], s 18.4 16.5 17.8 17.6 12.2 23.1 𝑫𝐚𝐜𝐭[b], mJ/cm2 82.8 74.3 80.1 79.2 54.9 103.4 𝒔𝟏𝟎[c], % 91.4 80.5 92.0 40.5 26.9 48.8 [a] The activation time 𝑡!"# of a PLT is defined by the time required to reach half of its maximum phosphorescen...

work page doi:10.1021/jacs.4c14920 2025
[2]

Flexible

(14) Kantelberg, R.; Achenbach, T.; Kirch, A.; Reineke, S. In-Plane Oxygen Diffusion Measurements in Polymer Films Using Time-Resolved Imaging of Programmable Luminescent Tags. Sci. Rep. 2024, 14 (1), 1–12. https://doi.org/10.1038/s41598-024-56237-5. (15) Tsiko, U.; Fidelius, J.; Kaiser, S.; Thomas, H.; Bui Thi, Y .; Weigand, J. J.; Grazulevicius, J. V .;...

work page doi:10.1038/s41598-024-56237-5 2024
[3]

(23) Meng, Y .; Liu, W.; Liu, Z.; Gao, M.; Fang, M.; Yang, J.; Ma, D.; Li, Z

https://doi.org/10.3389/fchem.2021.810304. (23) Meng, Y .; Liu, W.; Liu, Z.; Gao, M.; Fang, M.; Yang, J.; Ma, D.; Li, Z. Pure Room Temperature Phosphorescence Emission in Nondoped OLEDs: Adjustable Oxidation States and Excited-State Modulation. ACS Appl. Mater. Interfaces 2024, 16 (44), 60658–60665. https://doi.org/10.1021/acsami.4c13336. (24) Chen, J.; T...

work page doi:10.3389/fchem.2021.810304 2021
[4]

A new hybrid exchange-correlation func- tional using the Coulomb-attenuating method (CAM- 17 B3LYP).Chemical Physics Letters, 393(1):51– 57, 2004

(34) Neese, F. Software Update: The ORCA Program System — Version 6.0. Wiley Interdiscip. Rev. Comput. Mol. Sci. 2025, 15 (2), e70019. https://doi.org/0.1002/wcms.70019. (35) Yanai, T.; Tew, D. P.; Handy, N. C. A New Hybrid Exchange–Correlation Functional Using the Coulomb-Attenuating Method (CAM-B3LYP). Chem. Phys. Lett. 2004, 393 (1–3), 51–57. https://d...

work page doi:10.1016/j.cplett.2004.06.011 2025
[5]

decomposition

https://doi.org/10.1021/jacs.3c00058 (39) Fidelius, J.; Schwedtmann, K.; Schellhammer, S.; Haberstroh, J.; Schulz, S.; Huang, R.; Klotzsche, M. C.; Bauzá, A.; Frontera, A.; Reineke, S.; Weigand, J. J. Convenient Access to π-Conjugated 1,3-Azaphospholes from Alkynes via [3 + 2]-Cycloaddition and Reductive Aromatization. Chem 2024, 10 (2), 644–659. https://...

work page doi:10.1021/jacs.3c00058 2024

[1] [1]

ArtOfRTP

Key performance metrics of different RTP emitters in PLTs at 5 wt% in PS. Emitter Py-2TA PX-Py-TA TA Py-2PX Py-PX PX 𝒕𝐚𝐜𝐭[a], s 18.4 16.5 17.8 17.6 12.2 23.1 𝑫𝐚𝐜𝐭[b], mJ/cm2 82.8 74.3 80.1 79.2 54.9 103.4 𝒔𝟏𝟎[c], % 91.4 80.5 92.0 40.5 26.9 48.8 [a] The activation time 𝑡!"# of a PLT is defined by the time required to reach half of its maximum phosphorescen...

work page doi:10.1021/jacs.4c14920 2025

[2] [2]

Flexible

(14) Kantelberg, R.; Achenbach, T.; Kirch, A.; Reineke, S. In-Plane Oxygen Diffusion Measurements in Polymer Films Using Time-Resolved Imaging of Programmable Luminescent Tags. Sci. Rep. 2024, 14 (1), 1–12. https://doi.org/10.1038/s41598-024-56237-5. (15) Tsiko, U.; Fidelius, J.; Kaiser, S.; Thomas, H.; Bui Thi, Y .; Weigand, J. J.; Grazulevicius, J. V .;...

work page doi:10.1038/s41598-024-56237-5 2024

[3] [3]

(23) Meng, Y .; Liu, W.; Liu, Z.; Gao, M.; Fang, M.; Yang, J.; Ma, D.; Li, Z

https://doi.org/10.3389/fchem.2021.810304. (23) Meng, Y .; Liu, W.; Liu, Z.; Gao, M.; Fang, M.; Yang, J.; Ma, D.; Li, Z. Pure Room Temperature Phosphorescence Emission in Nondoped OLEDs: Adjustable Oxidation States and Excited-State Modulation. ACS Appl. Mater. Interfaces 2024, 16 (44), 60658–60665. https://doi.org/10.1021/acsami.4c13336. (24) Chen, J.; T...

work page doi:10.3389/fchem.2021.810304 2021

[4] [4]

A new hybrid exchange-correlation func- tional using the Coulomb-attenuating method (CAM- 17 B3LYP).Chemical Physics Letters, 393(1):51– 57, 2004

(34) Neese, F. Software Update: The ORCA Program System — Version 6.0. Wiley Interdiscip. Rev. Comput. Mol. Sci. 2025, 15 (2), e70019. https://doi.org/0.1002/wcms.70019. (35) Yanai, T.; Tew, D. P.; Handy, N. C. A New Hybrid Exchange–Correlation Functional Using the Coulomb-Attenuating Method (CAM-B3LYP). Chem. Phys. Lett. 2004, 393 (1–3), 51–57. https://d...

work page doi:10.1016/j.cplett.2004.06.011 2025

[5] [5]

decomposition

https://doi.org/10.1021/jacs.3c00058 (39) Fidelius, J.; Schwedtmann, K.; Schellhammer, S.; Haberstroh, J.; Schulz, S.; Huang, R.; Klotzsche, M. C.; Bauzá, A.; Frontera, A.; Reineke, S.; Weigand, J. J. Convenient Access to π-Conjugated 1,3-Azaphospholes from Alkynes via [3 + 2]-Cycloaddition and Reductive Aromatization. Chem 2024, 10 (2), 644–659. https://...

work page doi:10.1021/jacs.3c00058 2024