ORCID Profile
0000-0002-4874-141X
Current Organisation
Hong Kong Polytechnic University
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Publisher: Springer Science and Business Media LLC
Date: 10-08-2021
DOI: 10.1038/S41467-021-25148-8
Abstract: Graded bulk-heterojunction (G-BHJ) with well-defined vertical phase separation has potential to surpass classical BHJ in organic solar cells (OSCs). In this work, an effective G-BHJ strategy via nonhalogenated solvent sequential deposition is demonstrated using nonfullerene acceptor (NFA) OSCs. Spin-coated G-BHJ OSCs deliver an outstanding 17.48% power conversion efficiency (PCE). Depth-profiling X-ray photoelectron spectroscopy (DP-XPS) and angle-dependent grazing incidence X-ray diffraction (GI-XRD) techniques enable the visualization of polymer/NFA composition and crystallinity gradient distributions, which benefit charge transport, and enable outstanding thick OSC PCEs (16.25% for 300 nm, 14.37% for 500 nm), which are among the highest reported. Moreover, the nonhalogenated solvent enabled G-BHJ OSC via open-air blade coating and achieved a record 16.77% PCE. The blade-coated G-BHJ has drastically different D-A crystallization kinetics, which suppresses the excessive aggregation induced unfavorable phase separation in BHJ. All these make G-BHJ a feasible and promising strategy towards highly efficient, eco- and manufacture friendly OSCs.
Publisher: Springer Science and Business Media LLC
Date: 28-10-2021
DOI: 10.1038/S41467-021-26510-6
Abstract: The bulk morphology of the active layer of organic solar cells (OSCs) is known to be crucial to the device performance. The thin film device structure breaks the symmetry into the in-plane direction and out-of-plane direction with respect to the substrate, leading to an intrinsic anisotropy in the bulk morphology. However, the characterization of out-of-plane nanomorphology within the active layer remains a grand challenge. Here, we utilized an X-ray scattering technique, Grazing-incident Transmission Small-angle X-ray Scattering (GTSAXS), to uncover this new morphology dimension. This technique was implemented on the model systems based on fullerene derivative (P3HT:PC 71 BM) and non-fullerene systems (PBDBT:ITIC, PM6:Y6), which demonstrated the successful extraction of the quantitative out-of-plane acceptor domain size of OSC systems. The detected in-plane and out-of-plane domain sizes show strong correlations with the device performance, particularly in terms of exciton dissociation and charge transfer. With the help of GTSAXS, one could obtain a more fundamental perception about the three-dimensional nanomorphology and new angles for morphology control strategies towards highly efficient photovoltaic devices.
Publisher: Springer Science and Business Media LLC
Date: 02-12-2021
DOI: 10.1038/S41377-021-00676-6
Abstract: The benchmark tin oxide (SnO 2 ) electron transporting layers (ETLs) have enabled remarkable progress in planar perovskite solar cell (PSCs). However, the energy loss is still a challenge due to the lack of “hidden interface” control. We report a novel ligand-tailored ultrafine SnO 2 quantum dots (QDs) via a facile rapid room temperature synthesis. Importantly, the ligand-tailored SnO 2 QDs ETL with multi-functional terminal groups in situ refines the buried interfaces with both the perovskite and transparent electrode via enhanced interface binding and perovskite passivation. These novel ETLs induce synergistic effects of physical and chemical interfacial modulation and preferred perovskite crystallization-directing, delivering reduced interface defects, suppressed non-radiative recombination and elongated charge carrier lifetime. Power conversion efficiency (PCE) of 23.02% (0.04 cm 2 ) and 21.6% (0.98 cm 2 , V OC loss: 0.336 V) have been achieved for the blade-coated PSCs (1.54 eV E g ) with our new ETLs, representing a record for SnO 2 based blade-coated PSCs. Moreover, a substantially enhanced PCE ( V OC ) from 20.4% (1.15 V) to 22.8% (1.24 V, 90 mV higher V OC , 0.04 cm 2 device) in the blade-coated 1.61 eV PSCs system, via replacing the benchmark commercial colloidal SnO 2 with our new ETLs.
No related grants have been discovered for Kuan Liu.