I. Core Research Summary

• High-performance, degradable TADF system with nearly tenfold efficiency enhancement.

The tert-butyl ester group does not disrupt the TADF exciton reverse intersystem crossing mechanism, yielding a pure polymer light‑emitting device with an external quantum efficiency (EQE) of 10.4%. In host–guest doped systems, the maximum EQE reaches 15.1%, significantly exceeding that of previously reported degradable luminescent materials (≤1.5%) and matching the performance of commercial non‑degradable organic light‑emitting materials.

• Dual‑controlled depolymerization enables closed‑loop material recycling.

In a mildly acidic environment (pH 1.2), the polymer undergoes slow chain scission over 4 days; upon heating in nitrogen at 210°C for 1 hour, it fully depolymerizes into high-purity dicarboxylic acid monomers. These monomers can be re‑polymerized to regenerate the TADF polymer, with nearly no degradation in optoelectronic performance, enabling a closed‑loop recycling process.

• Aerosol jetting enables direct, maskless printing of fine optical anti-counterfeiting patterns.

Optomec’s AJ equipment is configured to dispense luminescent polymer inks, enabling precise microscale printing of QR‑based invisible luminescent codes on glass and flexible substrates. Following high‑temperature treatment, the luminescent patterns can be selectively erased, realizing thermally triggered hidden cryptographic optical identifiers.

• Excellent molecular structural stability, with no depolymerization during service life.

The tert-butyl ester linkage exhibits stability under ambient‑temperature operating conditions and undergoes controlled degradation only upon specific external stimuli—heat or acid—thereby balancing long‑term device performance with environmentally benign end‑of‑life disposal.

• A universal molecular design strategy that can be extended to all classes of luminescent materials.

A versatile modification strategy based on cleavable ester linkages enables the preparation of luminescent guest‑polymer systems and is compatible with high‑triplet‑energy‑gap host materials, supporting a wide range of TADF, fluorescent, and phosphorescent optoelectronic architectures.

II. Complete Preparation Procedure for Aerosol-Sprayed Luminescent Patterns

(1) Preparation Procedure

• The biodegradable TADF polymer is soluble in a chlorobenzene/NMP mixed solvent, enabling the formulation of stable luminescent functional inks.
• Plasma surface activation of clean glass, PET flexible substrates, and more;
• AJ aerosol system ultrasonic atomization luminescent ink, with sheath‑gas focusing for maskless direct printing of custom QR codes and dot‑matrix optical patterns.
• Low-temperature drying removes the solvent, completing the formation of the luminescent thin film.
• OLED devices can be assembled directly, or used for optical anti-counterfeiting; discarded samples are thermally treated to recover monomers for reuse.

(II) Five Core Advantages of Aerosol-Based Processes (Comparison with Spin Coating and Lithography)

• Digital Maskless Free-Printing Anti-Counterfeiting Micro-Patterns

No photolithography or plate-making is required; CAD‑based designs enable invisible, luminous QR codes and miniature optical identifiers, with rapid prototyping for small‑batch encrypted samples.

• Compatible with a variety of flexible and rigid substrates, suitable for transient electronics.

Non-contact aerosol deposition enables the fabrication of planar and mildly curved substrates, such as PET and glass, and is compatible with biodegradable, flexible optoelectronic medical devices.

• Localized ink deposition significantly reduces the consumption of expensive luminescent polymers.

Functional materials are deposited only in the patterned areas, while spin-coating a full‑wafer coating leads to significant material waste, thereby substantially reducing the R&D costs of rare‑earth luminescent materials.

• The film thickness is uniform and controllable, ensuring consistent device luminance.

Aerosol‑based layer‑by‑layer deposition yields films with excellent uniformity, eliminating edge‑to‑edge thickness variations associated with spin coating, and resulting in large‑area light‑emitting arrays with minimal brightness fluctuations.

• Low-temperature molding process that does not compromise the molecular structure of biodegradable polymers.

After printing, the material is dried at low temperature; no high-temperature processing steps are involved throughout the entire procedure, thereby preventing premature thermal degradation of the TADF molecules and preserving their full, controllable depolymerization behavior.

III. Five Core Technological Innovations of This Study

Innovation 1: A Universal Design for TADF Molecules with Cleavable tert-Butyl Ester Linkages

Innovative 2‑Stage Thermal/Acid Dual‑Trigger Controllable Closed‑Loop Recovery System

Innovative Prototype of Aerosol Direct-Print Thermal-Erasable Invisible Optical Anti-Counterfeiting Technology

Innovative 4-Component Biocompatible Degradable Luminescent System: Dual Adaptation of Donor and Acceptor

Innovative 5‑Green Aerosol Additive Manufacturing + Closed-Loop Material Integration Solution

IV. Current Industry Challenges in the Process and Corresponding Breakthrough Solutions

Challenge 1: Traditional biodegradable luminescent materials suffer from significant exciton losses, resulting in extremely low luminous efficiency.

Challenge 2: Degradation and usage cannot be separated, leading to easy device failure during operation.

Challenge 3: The luminescent thin film can only be prepared by spin-coating an entire sheet, making it impossible to fabricate fine anti-counterfeiting patterns.

Challenge 4: Waste luminescent electronics cannot be recycled, leading to organic microplastic pollution.

Challenge 5: Conventional lithography processes damage degradable flexible substrates and are costly.

V. Future Diversified Industrial Application Scenarios

1. Disposable medical transient optoelectronic device

2. Eco-friendly Flexible Displays and Lightweight Luminescent Labels

3. Thermally Erasable Invisible Optical Anti-Counterfeiting Marking

4 Agricultural Single-Use Photostimulating Film for Plants

5. Rapid R&D Platform for Optoelectronic Materials in the Laboratory

Figure 1 | Depolymerizable luminescent polymers based on the TADF mechanism and cleavable chemistry. a, Design principle of depolymerizable TADF polymers achieved by incorporating TB‑ester cleavable linkages into the polymer backbone; lifetime of the depolymerizable TADF polymer synthesized via Suzuki polycondensation, its performance in various potential applications, and a lifetime‑management strategy involving depolymerization to recover pure monomers. b, Schematic illustration of introducing TB‑ester cleavable linkages into two functional materials—polymeric TADF emitters and polymeric TADF hosts for EL devices—and the associated depolymerization mechanism. c, Schematic representations of the pristine polymer, the oligomeric products generated upon acidic depolymerization, and the pure monomeric products obtained through thermal depolymerization. d, Prototype application of depolymerizable polymers in information storage and security: a glass slide bearing a QR code is placed on a heated plate under a nitrogen atmosphere and treated at 210 °C for 1 hour to erase the pattern, after which images are captured at room temperature; time‑lapse images are shown in Supplementary Figure 20. Photostimulation is performed using a Thorlabs CS20 UV LED system (wavelength 365 nm).

Figure 2 | Photoluminescence (PL) and electroluminescence (EL) properties of the depolymerizable TADF polymer PDKCE. a. Chemical structures of the depolymerizable TADF polymer PDKCE and its reference polymer PDKCM, along with the TADF mechanism: S0, S1, and T1 denote the ground state, lowest singlet state, and lowest triplet state, respectively; ISC and RISC stand for intersystem crossing and reverse intersystem crossing, respectively; Fp and Fd correspond to prompt fluorescence and delayed fluorescence, respectively. b. HOMO, LUMO, HOMO‑1, and LUMO+1 energy levels in the minimal electronic conjugated unit of PDKCE and PDKCM, as calculated by density functional theory. c. Absorption spectra and room‑temperature emission spectra of PDKCE and PDKCM thin films (emission spectra measured in air under 310 nm excitation). d. PL transient decay curves and PL quantum yields of PDKCE and PDKCM (inset). e. Schematic diagram of an OLED used to characterize the EL performance of PDKCE and PDKCM as carrier‑free EML materials. f, g. Representative current–brightness–voltage curves (f), EQE–current density curves (g), and normalized EL spectra (inset in g) for PDKCE and PDKCM.

Figure 3 | Depolymerization behavior of PDKCE. a, Number-average molecular weights (Mn) of PDKCE and PDKCM monitored over time in a THF/hydrochloric acid mixture; b, TGA curves of PDKCE and PEKCM under a nitrogen atmosphere at a heating rate of 15 °C·min⁻¹; c, TGA curves of PDKCE at different final temperatures, starting from 25 °C with an initial heating rate of 15 °C·min⁻¹ in a nitrogen atmosphere; d, Chemical structure, appearance, and ¹H NMR spectra of PDKCE before and after thermal depolymerization.

Figure 4 | Recyclability of the TADF moiety in PDKCE. a, The TADF moiety from the depolymerization product DKCOOH is recovered into DKCE via esterification. b, c, Spatial distribution of holes and electrons and energy-level diagrams for DKCOOH (b) and DKCE (c) in the T1 state. A–D1 and A–D2 denote the charge-transfer states of the benzophenone–acridine and benzophenone–carbazole A–D pairs, respectively. d, Time-resolved streak‑camera images of PDKCE and its depolymerization product DKCOOH (after heating), as well as the re‑esterified product DKCE, over the 0–5 µs time window at room temperature. Depolymerization was carried out by heating in an N₂ atmosphere at 210 °C for 1 hour. e–g, Performance of OLED devices fabricated using the recovered DKCE: representative current density–brightness–voltage curves (e), EQE–current density and current efficiency–current density plots (f), and the electroluminescence spectrum of an OLED with the recovered DKCE as the EML (g). OLED architecture: ITO / PEDOT:PSS (60 nm) / DKCE (40 nm) / TPBI (55 nm) / lithium fluoride (1 nm) / aluminum.

Figure 5 | Depolymerizable‑backbone polymer PC6E. a) Schematic of the EML composed of a host–guest system, along with the chemical structures of the depolymerizable backbone polymer PC6E and the guest molecule tBuCzDBA used in this study (tBuCzDBA = 9,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl)-2,6-dimethylphenyl)-9,10-diboranthene). b) Time‑dependent evolution of the number‑average molecular weight (Mn) of PC6E as monitored in a THF/hydrochloric acid mixture. c) TGA curve of PC6E under a nitrogen atmosphere at a heating rate of 15 °C·min⁻¹. d) Absorption spectrum of PC6E thin films and their low‑temperature (77 K) phosphorescence spectra in a 2‑methyltetrahydrofuran solution. e) Energy level diagram of the materials employed in OLED experiments to characterize the electroluminescent properties of PC6E. f) and g) Representative current density–brightness–voltage curves (f) and current density–EQE curves (g) for OLED devices using PC6E/x wt.% tBuCzDBA as the EML, with varying doping concentrations (10%, 20%, 30%, 40%, and 100%).