Suchergebnisse

Polyvinylpyrrolidone (PVP) has been successfully used as the cathode interfacial layer (CIL) in organic solar cells (OSCs) for work function (W-F) modification. However, detailed insight into the effect of a PVP interlayer on the physicochemical properties of the indium tin oxide (ITO) electrode in inverted OSCs (I-OSCs) is still largely absent. Herein, the ITO/PVP interface is investigated by photoelectron spectroscopy and the mechanisms for the energy level alignment of PVP on different substrates in general are unraveled. The results indicate that the dipole formation that reduces the W-F is driven by not only the directional intrinsic molecular dipole moments associated with the gamma-lactam of PVP, but also an additional dipole step with the same direction created by the image charges in the contacting (semi-)conductor layer. In addition, high-performance inverted OSCs (I-OSCs) are achieved by introducing a self-assembled ultrathin PVP layer using a simple immersion method. This work provides enhanced understanding of the PVP-based CIL and demonstrates its great potential in I-OSC fabrication, which can pave the way to simplified manufacturing of low-cost and large-area devices in organic electronic technologies. ; Funding Agencies|Swedish Energy AgencySwedish Energy Agency [45411-1]; Swedish Research CouncilSwedish Research Council [2016-05498, 2016-05990]; STINT grant [CH2017-7163]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Wallenberg Wood Science Center (WWSC) [KAW 2018.0452]

Nanostructures of conventional metals offer manipulation of light at the nanoscale but are largely limited to static behavior due to fixed material properties. To develop the next frontier of dynamic nano-optics and metasurfaces, this study utilizes the redox-tunable optical properties of conducting polymers, as recently shown to be capable of sustaining plasmons in their most conducting oxidized state. Electrically tunable conducting polymer nano-optical antennas are presented, using nanodisks of poly(3,4-ethylenedioxythiophene:sulfate) (PEDOT:Sulf) as a model system. In addition to repeated on/off switching of the polymeric nanoantennas, the concept enables gradual electrical tuning of the nano-optical response, which was found to be related to the modulation of both density and mobility of the mobile polaronic charge carriers in the polymer. The resonance position of the PEDOT:Sulf nanoantennas can be conveniently controlled by disk size, here reported down to a wavelength of around 1270 nm. The presented concept may be used for electrically tunable metasurfaces, with tunable farfield as well as nearfield. The work thereby opens for applications ranging from tunable flat meta-optics to adaptable smart windows. ; Funding Agencies|Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; Swedish Research Council (VR)Swedish Research Council [2020-00287]; Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]

Solar energy, although it has the highest power density available in terms of renewable energy, has the drawback of being erratic. Integrating an energy harvesting and storage device into photovoltaic energy storage modules is a viable route for obtaining self-powered energy systems. Herein, an MXene-based all-solution processed semitransparent flexible photovoltaic supercapacitor (PSC) was fabricated by integrating a flexible organic photovoltaic (OPV) with Ti3C2Tx MXene as the electrode and transparent MXene supercapacitors with an organic ionogel as the electrolyte in the vertical direction, using Ti3C2Tx thin film as a common electrode. In the quest for a semitransparent flexible PSC, Ti3C2Tx MXene was first used as a transparent electrode for OPV with a high power conversion efficiency of 13.6%. The ionogel electrolyte-based transparent MXene supercapacitor shows a high volumetric capacitance of 502 F cm(-3) and excellent stability. Finally, a flexible PSC with a high average transmittance of over 33.5% was successfully constructed by all-solution processing and a remarkable storage efficiency of 88% was achieved. This strategy enables a simple route for fabricating MXene based high-performance all-solution-processed flexible PSCs, which is important for realizing flexible and printable electronics for future technologies. ; Funding Agencies|Swedish Energy AgencySwedish Energy Agency [EM 42033-1]; Swedish Government Strategic Research Area in Material Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [200900971]; Swedish Research CouncilSwedish Research Council [2017-04123]; SSF Research Infrastructure Fellow Program [RIF 14-0074]; SSF Synergy Program [EM16-0004]; Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [61774077]; Open Fund of the State Key Laboratory of Luminescent Materials and Devices [2018-skllmd-12]; Fundamental Research Funds for the Central UniversitiesFundamental Research Funds for the Central Universities

Matched energy level alignment is a key requirement for efficient organic devices such as organic light-emitting diodes, photovoltaics, and field-effect transistors. The effect of thermal stress/annealing on energy level alignment and related properties of the devices are less discussed compared to the extensively explored effect on morphology and corresponding device performance. Here all polymer solar cells (all-PSCs) are employed to study thermal annealing effects on energy level alignment and the corresponding effect on the device properties of the all-PSCs. It is found that optimized energy level alignment can be achieved by thermal annealing. An interface dipole layer at the donor/acceptor interface is introduced by energy level realignment that assists charge generation by reducing geminate recombination so that the voltage loss is dramatically reduced, improving the performance of the all-PSCs. ; Funding Agencies|Knut and Alice Wallenberg Foundation project "Tail of the Sun"; Swedish Research CouncilSwedish Research Council [2016-05498]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [SE13-0060]; Swedish Energy AgencySwedish Energy Agency [45411-1]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]

To achieve high-performance perovskite light-emitting diodes (PeLEDs), an appropriate functional layer beneath the perovskite emissive layer is significantly important to modulate the morphology of the perovskite film and to facilitate charge injection and transport in the device. Herein, for the first time, we report efficient n-i-p structured PeLEDs using solution-processed SnO2 as an electron transport layer. Three-dimensional perovskites, such as CH(NH2)(2)PbI3 and CH3NH3PbI3, are found to be more chemically compatible with SnO2 than with commonly used ZnO. In addition, SnO2 shows good transparency, excellent morphology and suitable energy levels. These properties make SnO2 a promising candidate in both three-and low-dimensional PeLEDs, among which a high external quantum efficiency of 7.9% has been realized. Furthermore, interfacial materials that are widely used to improve the device performances of ZnO-based PeLEDs are also applied on SnO2-based PeLEDs and their effects have been systematically studied. In contrast to ZnO, SnO2 modified by these interfacial materials shows detrimental effects due to photoluminescence quenching. ; Funding Agencies|ERC [717026]; Carl Tryggers Stiftelse; China Scholarship Council; European Commission Marie Sklodowska-Curie Actions [691210]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Vinnova; Marie Sklodowska-Curie Fellow [2016-02051]; State Key Laboratory of Luminescent Materials and Devices at South China University of Technology [2017-skllmd-05]; State Key Lab of Silicon Materials at Zhejiang University [SKL2017-03]

Energy level alignment (ELA) at donor-acceptor heterojunctions is of vital importance yet largely undetermined in organic solar cells. Here, authors determine the heterojunction ELA with (mono) layer-by-layer precision to understand the co-existence of efficient charge. 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. ; Funding Agencies|Swedish Research Council [2016-05498, 2016-05990, 2020-04538, 2018-06048, 2018-07152]; Swedish Energy Agency [45411-1]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Wallenberg Wood Science Center (WWSC); Stiftelsen for Strategisk Forskning through a Future Research Leader program [FFL18-0322]; Swedish Governmental Agency for Innovation Systems [2018-04969]; Formas [2019-02496]