Qilun Zhang

All Publications

• Interfacial Potential Compensation for HOMO Alignment in Ternary Organic Solar Cells. Small (Weinheim an der Bergstrasse, Germany) Gao, Z., Li, W., Liu, H., Li, X., Zhang, Q., Liu, T., Li, H., Liu, X., Yu, L., Bao, X., Xu, X., Ding, L., McCulloch, I., Lu, X., Fahlman, M., Wang, C. 2026: e74562

  Abstract

  Conventional energetic design rules for ternary organic solar cells (OSCs) often overlook interfacial potential shifts, leading to an incomplete understanding of energy-level alignment (ELA) based on the idealized vacuum-level assumption. In this work, we reveal that these hidden potential steps, together with the formation of an alloy donor morphology, are the key to unlocking high-performance ternary blends. By utilizing the monolayer-by-monolayer Langmuir-Schaefer method combined with photoelectron spectroscopy, we directly characterized the ELA at each donor and acceptor interface within the ternary blends. We show that the two donors, possessing complementary absorption profiles, exhibit synchronized contact-induced potential steps at their respective interfaces with the acceptor. This potential compensation precisely offsets the intrinsic HOMO offsets measured in neat films, resulting in a fully aligned and unified HOMO-level landscape across the ternary blend. This configuration provides the physical solution to reconcile efficient charge generation with a maximized photovoltaic gap. Our findings highlight that integrating morphological alloying with synchronized potential compensation provides a robust framework for understanding and rationally engineering the complex electronic landscapes of multi-component OSCs.

  View details for DOI 10.1002/smll.74562

  View details for PubMedID 42429218

• Facile-processed n-p-type binary cathode interlayers: Concurrent enhancement of photovoltaic performance and mechanical robustness NANO ENERGY Li, W., Wang, X., Liu, H., Zhang, Q., Li, X., Liu, T., Liu, C., Xu, X., Yu, L., Bao, X., Liu, X., Mcculloch, I., Ding, L., Lu, X., Fahlman, M., Wang, C. 2026; 149

  View details for DOI 10.1016/j.nanoen.2026.111702

  View details for Web of Science ID 001667878900001

• Autonomous aqueous H₂O₂ production with a carboxylate-functionalized polythiophene JOURNAL OF MATERIALS CHEMISTRY A Bruschi, C., Shimolo, A., Heimonen, J., Zhang, Q., Fahlman, M., Vagin, M., Kroon, R. 2025

  View details for DOI 10.1039/d5ta07162c

  View details for Web of Science ID 001625622300001

• Ground-state electron transfer in all-polymer donor:acceptor blends enables aqueous processing of water-insoluble conjugated polymers NATURE COMMUNICATIONS Liu, T., Heimonen, J., Zhang, Q., Yang, C., Huang, J., Wu, H., Stoeckel, M., van der Pol, T. P. A., Li, Y., Jeong, S., Marks, A., Wang, X., Puttisong, Y., Shimolo, A. Y., Liu, X., Zhang, S., Li, Q., Massetti, M., Chen, W. M., Woo, H., Pei, J., McCulloch, I., Gao, F., Fahlman, M., Kroon, R., Fabiano, S. 2023; 14 (1): 8454

  Abstract

  Water-based conductive inks are vital for the sustainable manufacturing and widespread adoption of organic electronic devices. Traditional methods to produce waterborne conductive polymers involve modifying their backbone with hydrophilic side chains or using surfactants to form and stabilize aqueous nanoparticle dispersions. However, these chemical approaches are not always feasible and can lead to poor material/device performance. Here, we demonstrate that ground-state electron transfer (GSET) between donor and acceptor polymers allows the processing of water-insoluble polymers from water. This approach enables macromolecular charge-transfer salts with 10,000× higher electrical conductivities than pristine polymers, low work function, and excellent thermal/solvent stability. These waterborne conductive films have technological implications for realizing high-performance organic solar cells, with efficiency and stability superior to conventional metal oxide electron transport layers, and organic electrochemical neurons with biorealistic firing frequency. Our findings demonstrate that GSET offers a promising avenue to develop water-based conductive inks for various applications in organic electronics.

  View details for DOI 10.1038/s41467-023-44153-7

  View details for Web of Science ID 001130478800004

  View details for PubMedID 38114560

  View details for PubMedCentralID PMC10730874

• Industrial Kraft Lignin Based Binary Cathode Interface Layer Enables Enhanced Stability in High Efficiency Organic Solar Cells ADVANCED MATERIALS Zhang, Q., Liu, T., Wilken, S., Xiong, S., Zhang, H., Ribca, I., Liao, M., Liu, X., Kroon, R., Fabiano, S., Gao, F., Lawoko, M., Bao, Q., Oesterbacka, R., Johansson, M., Fahlman, M. 2024; 36 (9): e2307646

  Abstract

  Herein, a binary cathode interface layer (CIL) strategy based on the industrial solvent fractionated LignoBoost kraft lignin (KL) is adopted for fabrication of organic solar cells (OSCs). The uniformly distributed phenol moieties in KL enable it to easily form hydrogen bonds with commonly used CIL materials, i.e., bathocuproine (BCP) and PFN-Br, resulting in binary CILs with tunable work function (WF). This work shows that the binary CILs work well in OSCs with large KL ratio compatibility, exhibiting equivalent or even higher efficiency to the traditional CILs in state of art OSCs. In addition, the combination of KL and BCP significantly enhanced OSC stability, owing to KL blocking the reaction between BCP and nonfullerene acceptors (NFAs). This work provides a simple and effective way to achieve high-efficient OSCs with better stability and sustainability by using wood-based materials.

  View details for DOI 10.1002/adma.202307646

  View details for Web of Science ID 001126669100001

  View details for PubMedID 37812198

• Switchable Broadband Terahertz Absorbers Based on Conducting Polymer-Cellulose Aerogels ADVANCED SCIENCE Kuang, C., Chen, S., Luo, M., Zhang, Q., Sun, X., Han, S., Wang, Q., Stanishev, V., Darakchieva, V., Crispin, R., Fahlman, M., Zhao, D., Wen, Q., Jonsson, M. P. 2024; 11 (3): e2305898

  Abstract

  Terahertz (THz) technologies provide opportunities ranging from calibration targets for satellites and telescopes to communication devices and biomedical imaging systems. A main component will be broadband THz absorbers with switchability. However, optically switchable materials in THz are scarce and their modulation is mostly available at narrow bandwidths. Realizing materials with large and broadband modulation in absorption or transmission forms a critical challenge. This study demonstrates that conducting polymer-cellulose aerogels can provide modulation of broadband THz light with large modulation range from ≈ 13% to 91% absolute transmission, while maintaining specular reflection loss < -30 dB. The exceptional THz modulation is associated with the anomalous optical conductivity peak of conducting polymers, which enhances the absorption in its oxidized state. The study also demonstrates the possibility to reduce the surface hydrophilicity by simple chemical modifications, and shows that broadband absorption of the aerogels at optical frequencies enables de-frosting by solar-induced heating. These low-cost, aqueous solution-processable, sustainable, and bio-friendly aerogels may find use in next-generation intelligent THz devices.

  View details for DOI 10.1002/advs.202305898

  View details for Web of Science ID 001109051600001

  View details for PubMedID 37997181

  View details for PubMedCentralID PMC10797431

• <i>In situ</i> near-ambient pressure X-ray photoelectron spectroscopy reveals the effects of water, oxygen and light on the stability of PM6:Y6 photoactive layers JOURNAL OF MATERIALS CHEMISTRY C Zhang, Q., Chen, Y., Liu, X., Fahlman, M. 2023; 11 (8): 3112-3118

  View details for DOI 10.1039/d2tc04378e

  View details for Web of Science ID 000933194400001

• Natural Product Betulin-Based Insulating Polymer Filler in Organic Solar Cells SOLAR RRL Zhang, Q., Zhang, H., Wu, Z., Wang, C., Zhang, R., Yang, C., Gao, F., Fabiano, S., Woo, H., Ek, M., Liu, X., Fahlman, M. 2022; 6 (9)

  View details for DOI 10.1002/solr.202200381

  View details for Web of Science ID 000809737000001

• Mapping the energy level alignment at donor/acceptor interfaces in non-fullerene organic solar cells NATURE COMMUNICATIONS Li, X., Zhang, Q., Yu, J., Xu, Y., Zhang, R., Wang, C., Zhang, H., Fabiano, S., Liu, X., Hou, J., Gao, F., Fahlman, M. 2022; 13 (1): 2046

  Abstract

  Energy level alignment (ELA) at donor (D) -acceptor (A) heterojunctions is essential for understanding the charge generation and recombination process in organic photovoltaic devices. However, the ELA at the D-A interfaces is largely underdetermined, resulting in debates on the fundamental operating mechanisms of high-efficiency non-fullerene organic solar cells. Here, we systematically investigate ELA and its depth-dependent variation of a range of donor/non-fullerene-acceptor interfaces by fabricating and characterizing D-A quasi bilayers and planar bilayers. In contrast to previous assumptions, we observe significant vacuum level (VL) shifts existing at the D-A interfaces, which are demonstrated to be abrupt, extending over only 1-2 layers at the heterojunctions, and are attributed to interface dipoles induced by D-A electrostatic potential differences. The VL shifts result in reduced interfacial energetic offsets and increased charge transfer (CT) state energies which reconcile the conflicting observations of large energy level offsets inferred from neat films and large CT energies of donor - non-fullerene-acceptor systems.

  View details for DOI 10.1038/s41467-022-29702-w

  View details for Web of Science ID 000784997300123

  View details for PubMedID 35440117

  View details for PubMedCentralID PMC9018783

• Understanding the Work Function Modification by a Self-assembled Polyvinylpyrrolidone Layer in Inverted Organic Solar Cells SOLAR RRL Zhang, Q., Wang, C., Liu, X., Fahlman, M. 2021; 5 (1)

  View details for DOI 10.1002/solr.202000575

  View details for Web of Science ID 000591905000001