| 1. |
- Andruszkiewicz, Aneta, et al.
(författare)
-
Perovskite and quantum dot tandem solar cells with interlayer modification for improved optical semitransparency and stability
- 2021
-
Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 13:12, s. 6234-6240
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, four-terminal (4T) tandem solar cells were fabricated by using a methylammonium lead iodide (MAPbI3) perovskite solar cell (PSC) as the front-cell and a lead sulfide (PbS) colloidal quantum dot solar cell (CQDSC) as the back-cell. Different modifications of the tandem interlayer, at the interface between the sub-cells, were tested in order to improve the infrared transparency of the perovskite sub-cell and consequently increase the utilization of infrared (IR) light by the tandem system. This included the incorporation of a semi-transparent thin gold electrode (Au) on the MAPbI3 solar cell, followed by adding a molybdenum(VI) oxide (MoO3) layer or a surlyn layer. These interlayer modifications resulted in an increase of the IR transmittance to the back cell and improved the optical stability, compared to that in the reference devices. This investigation shows the importance of the interlayer, connecting the PSC with a strong absorption in the visible region and the CQDSC with a strong infrared absorption to obtain efficient next-generation tandem photovoltaics (PVs).
|
|
| 2. |
- Baginski, Maciej, et al.
(författare)
-
Understanding and Controlling the Crystallization Process in Reconfigurable Plasmonic Superlattices
- 2021
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:3, s. 4916-4926
-
Tidskriftsartikel (refereegranskat)abstract
- The crystallization of nanomaterials is a primary source of solid-state, photonic structures. Thus, a detailed understanding of this process is of paramount importance for the successful application of photonic nanomaterials in emerging optoelectronic technologies. While colloidal crystallization has been thoroughly studied, for example, with advanced in situ electron microscopy methods, the noncolloidal crystallization (freezing) of nanoparticles (NPs) remains so far unexplored. To fill this gap, in this work, we present proof-of-principle experiments decoding a crystallization of reconfigurable assemblies of NPs at a solid state. The chosen material corresponds to an excellent testing bed, as it enables both in situ and ex situ investigation using X-ray diffraction ( XRD), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), atomic force microscopy (AFM), and optical spectroscopy in visible and ultraviolet range (UV-vis) techniques. In particular, ensemble measurements with small-angle XRD highlighted the dependence of the correlation length in the NPs assemblies on the number of heating/cooling cycles and the rate of cooling. Ex situ TEM imaging further supported these results by revealing a dependence of domain size and structure on the sample preparation route and by showing we can control the domain size over 2 orders of magnitude. The application of HAADF-STEM tomography, combined with in situ thermal control, provided three-dimensional single-particle level information on the positional order evolution within assemblies. This combination of real and reciprocal space provides insightful information on the anisotropic, reversibly reconfigurable assemblies of NPs. TEM measurements also highlighted the importance of interfaces in the polydomain structure of nanoparticle solids, allowing us to understand experimentally observed differences in UV-vis extinction spectra of the differently prepared crystallites. Overall, the obtained results show that the combination of in situ heating HAADF-STEM tomography with XRD and ex situ TEM techniques is a powerful approach to study nanoparticle freezing processes and to reveal the crucial impact of disorder in the solid-state aggregates of NPs on their plasmonic properties.
|
|
| 3. |
- Chen, Jingxuan, et al.
(författare)
-
Regulating Thiol Ligands of p-Type Colloidal Quantum Dots for Efficient Infrared Solar Cells
- 2021
-
Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 6:5, s. 1970-1989
-
Tidskriftsartikel (refereegranskat)abstract
- The p-type semiconducting colloidal quantum dot (CQD), working as a hole conductor in CQD solar cells (CQDSCs), is critical for charge carrier extraction and therefore, to large extent, determines the device's photovoltaic performance. However, during the preparation of a p-type CQD solid film on the top of an n-type CQD solid film, forming a p-n heterojunction within the CQDSCs, the optoelectronic properties of the underlayered n-type CQD solid film are significantly affected by conventional 1,2-ethanedithiol (EDT) ligands due to its high reactivity. Herein, a series of thiol ligands are comprehensively studied for p-type CQDs, which suggests that, by finely controlling the interaction between the CQDs and thiol ligands during the preparation of p-type CQD solid films, the n-type CQD solid films can be well protected and avoid destruction induced by thiol ligands. The p-type CQD solid film with 4-aminobenzenethiol (ABT) passivating the CQD surface exhibits better optoelectronic properties than the conventional p-type EDT-based CQD solid films, resulting in an improved photovoltaic performance in CQDSCs.
|
|
| 4. |
- Johansson, Erik, et al.
(författare)
-
Combining Quantum Dot and Perovskite Photovoltaic Cells for Efficient Photon to Electricity Conversion in Energy Storage Devices
- 2022
-
Ingår i: Energy Technology. - : John Wiley & Sons. - 2194-4288 .- 2194-4296. ; 10:10
-
Tidskriftsartikel (refereegranskat)abstract
- Renewable energy sources, such as wind and solar power, are increasingly important today to reduce emissions from fossil-based energy sources. However, the electricity from wind and solar power varies over time and depends on weather conditions and the time of the day. Therefore, to include a large fraction of electricity from these energy sources in the electricity grid, large-scale and low-cost energy storage is needed. Herein, it is investigated how a combination of quantum dot based photovoltaic cells and perovskite-based photovoltaic cells can be used to increase the energy conversion efficiency and increase the working range of energy storage devices based on conversion between heat, light, and electricity. The results show that these new types of photovoltaic materials have very promising properties for efficient utilization in energy storage devices, which have the potential for large-scale and low-cost energy storage.
|
|
| 5. |
- Sloboda, Tamara, et al.
(författare)
-
A method for studying pico to microsecond time-resolved core-level spectroscopy used to investigate electron dynamics in quantum dots
- 2020
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Time-resolved photoelectron spectroscopy can give insights into carrier dynamics and offers the possibility of element and site-specific information through the measurements of core levels. In this paper, we demonstrate that this method can access electrons dynamics in PbS quantum dots over a wide time window spanning from pico- to microseconds in a single experiment carried out at the synchrotron facility BESSY II. The method is sensitive to small changes in core level positions. Fast measurements at low pump fluences are enabled by the use of a pump laser at a lower repetition frequency than the repetition frequency of the X-ray pulses used to probe the core level electrons: Through the use of a time-resolved spectrometer, time-dependent analysis of data from all synchrotron pulses is possible. Furthermore, by picosecond control of the pump laser arrival at the sample relative to the X-ray pulses, a time-resolution limited only by the length of the X-ray pulses is achieved. Using this method, we studied the charge dynamics in thin film samples of PbS quantum dots on n-type MgZnO substrates through time-resolved measurements of the Pb 5d core level. We found a time-resolved core level shift, which we could assign to electron injection and charge accumulation at the MgZnO/PbS quantum dots interface. This assignment was confirmed through the measurement of PbS films with different thicknesses. Our results therefore give insight into the magnitude of the photovoltage generated specifically at the MgZnO/PbS interface and into the timescale of charge transport and electron injection, as well as into the timescale of charge recombination at this interface. It is a unique feature of our method that the timescale of both these processes can be accessed in a single experiment and investigated for a specific interface.
|
|
| 6. |
- Yuan, Lin, et al.
(författare)
-
Four-Terminal Tandem Solar Cell with Dye-Sensitized and PbS Colloidal Quantum-Dot-Based Subcells
- 2020
-
Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 3:4, s. 3157-3161
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, high-performance four-terminal solution-processed tandem solar cells were fabricated by using dye-sensitized solar cells (DSSCs) as top-cells and lead sulfide (PbS) colloidal quantum dot solar cells (CQDSCs) as bottom-cells. For dye-sensitized top-cells, three different dye combinations were used while the titanium dioxide (TiO2) scattering layer was removed to maximize the transmission. For the PbS bottom-cells, quantum dots with different sizes were compared. Over 12% power conversion efficiency has been achieved by using the XL dye mixture and 890 nm PbS QDs, which shows a significant efficiency enhancement when compared to single DSSC or CQDSC subcells.
|
|
