1. Academic Report 1: Emission Color Pureness and Efficiency Regulation in Organic Chromophores
Time: 10:00-12:00 AM, November 11, 2025
2. Tutorial: Bimolecular Quenching & Sensitization of Organic Chromophores
Time: 2:30-3:30 PM, November 11, 2025
3. Academic Report 2: Charge Transfer State Engineering for Tailor-Made Luminescent Organic Materials
Time: 9:00-11:00 AM, November 12, 2025
4. Scientific Integrity Seminar: Erosion of Scientific Integrity Fueled by Quantitative Evaluation Metrics
Time: 11:00 AM-12:00 PM, November 12, 2025
5. Young Researcher Course: Scientific Integrity Decline in Current Materials Research: Dimension, Origins, Elements, and Solutions
Time: 9:00 AM-12:00 PM, November 13, 2025
Abstract:
1. Emission Color Pureness and Efficiency Regulationin Organic Chromophores
Luminescent conjugated organic chromophores have found immense interest incurrent materials research, and rapid progress has been seen over the pastyears. In any case, the quest for sustainable research demands pre-synthesistailor-made targeted design beyond experimental (and computational)trial-and-error strategies. This can only be achieved by a thoroughunderstanding of the underlying photophysical process combined withspectroscopic and computational techniques. In this spirit, the seminar will focuson key parameters of emissive organic materials, being (1) luminescenceefficiency and (2) color purity, being both crucial in particular for OLEDresearch.
(1) Luminescence efficiency is decided by the competition of radiative vs.nonradiative processes. Nonradiative decay via internal conversion (IC) isfrequently tackled via 'Fermi's Golden Rule' (FGR).[1] However, in particularfor systems with very effective IC, FGR may break down both in a quantitativeand qualitative manner. This was especially shown for compound families whichestablish an 'inverted energy gap law', sharply contrasting the prediction ofFGR. Instead, this has to be treated via conical intersections (CIs). In thesolid state, IC becomes often a minor pathway, as the access to the CI ofteninvolves large amplitude motions,[2,3] giving rise to 'Solid State Luminescence Enhancement' (SLE).[1] On the other hand,examples of active CIs in solid state samples have been identified, due to theabsence of large amplitude motions on the path to the CI,[4] so that fluorescencequenching persists in molecular solids.
(2) Color purity, i.e. measured by the effective spectral width,[5] can be convenientlypredicted within commercial quantum chemistry program packages; however; whilethis generates quite accurate numbers, it does not provide understanding. Wewill show that such understanding ‒ 'beyond numbers' ‒ can be achieved at a simple conceptual basis using resonance theory andMO topology consideration; this allows for targeted 'paper and pencil'molecular design of color pure emitters, ranging from the UV to blue region[5] to the deep red/NIR.[6]
2. Charge Transfer State Engineering for Tailor-MadeLuminescent Organic Materials
In the past 20 years,all-organic chromophores were intensively investigated for application inmaterials conversion and life science applications. For the different purposes,color-specific, luminescent or non-luminescent, dissolved or aggregatedchromophores are targeted. In order to achieve this, increasingly complexmulti-channel photophysics are exploited, such as dual emission (DE),photoinduced electron transfer (PeT), RTP, TADF, TICT, or SLE/AIE inco-/crystals.[1] Charge transfer (CT)states play a central role in most of these processes. Tailor-made design ofsuch compounds is thus of high technological demand; it requires, however, adetailed understanding to ultimately control the multiple deactivationprocesses, inter alia modulated by inter-chromophore interactions. Thecomplexity of the underlying processes and their pivotal importance formaterials' performance poses however grand challenges; in fact, misconceptionsand false claims are frequently and increasingly found in this vivid area ofresearch. A breakthrough in targeted design can be therefore only achieved in aholistic manner, combining advanced spectroscopic and computational methods inan intimate interdisciplinary 'dual expertise' scheme, in fact followed in ourgroup.
The seminar will give insightto our recent activities to decipher complex photophysics of organic materialsinvolving CT states. This will include (i) exciplex-forming DE donor-acceptortriads for stimuli-responsive materials,[2] (ii) perylene-based deep-red solid state emittersthrough PeT regulation,[3] (iii)efficient TADF emitters for OLED vs. photocatalysis applications,[4] and (iv) solid statecolor regulation by intra- vs. intermolecular charge transfer (CT) states.[5] Following an overview on theseprocesses, we will detail selected examples to illustrate the in-depth analysisprocedure.
3. Tutorial：Bimolecular Quenching &Sensitization of Organic Chromophores
Besides his active combinedspectroscopic and computational research on organic and hybrid π-conjugatedchromophores, J. Gierschner is dedicated to consolidate the community knowledgethrough regular educative reviews,[1] as well as an international lecture series (30h) onPhotophysics of Conjugated Organic Materials, which he developed over the pasttwenty-five years.[2] The present Tutorialfocuses on a relevant chapter of this lecture, discussing Bimolecular Quenching& Sensitization pathways in solution and the solid state. After giving abrief overview on the various processes, discussing dynamic vs. staticquenching, and giving mechanistic insights to energy transfer (ET), andphotoinduced electron transfer (PeT) processes, we finally turn to solventquenching and solid state luminescence quenching (SLQ). We will in particularsee why quenching in molecular solids is, in the outmost cases, notaggregation-caused, but intimately related to morphology; this willexplain why single crystals of conjugated organic materials are usually highlyemissive, but become often low emissive in polycrystalline samples, caused byeffective exciton trapping. Strategies to overcome these limitations areoutlined in order to guide future targeted materials design.
Biography of Professor Johannes Gierschner
Johannes Gierschner received his Ph.D. in Physical Chemistry at the Univ. Tübingen, Germany, in 2000. After stays at Univ. Tübingen, at the Univ. of Mons (Belgium), and at Georgia Tech, Atlanta (USA), he joined the Madrid Institute for Advanced Studies - IMDEA Nanoscience - in 2008 as a Senior Research Professor (Ramón y Cajal fellow 2008-13). In 2014, he habilitated at Tübingen and holds an Adjunct Prof. position ('Privatdozent') there since then.
JG is regular visiting researcher at Univ. Valencia (since 2014), and at Seoul National University (SNU; since 2008), and held Visiting Professor positions at SNU and Univ. Mons (2014/15). His 160 papers integrate optical spectroscopy and computational chemistry to elucidate structure-property and -process relationships in conjugated organic materials for optoelectronics and energy conversion.
JG is further dedicated to consolidate the community knowledge through regular educative reviews, and international lecture series in 'Photophysics of Conjugated Organic Materials'. Moreover, during the last years, he is increasingly committed to 'Scientific Integrity' issues below the tip of the iceberg, providing seminars for junior and senior researchers.