| 1. |
|
|
| 2. |
- Zhang, Peili, et al.
(författare)
-
Gas-templating of hierarchically structured Ni-Co-P for efficient electrocatalytic hydrogen evolution
- 2017
-
Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 5:16, s. 7564-7570
-
Tidskriftsartikel (refereegranskat)abstract
- One of the grand challenges for developing scalable and sustainable hydrogen producing systems is the lack of efficient and robust earth-abundant element based catalysts for the hydrogen evolution reaction (HER). Herein, a hierarchically structured Ni-Co-P film was fabricated via a gas templating electro-deposition method. This film exhibits remarkably high catalytic performance for the HER in 1 M KOH with respective current densities of -10 and -500 mA cm(-2) at the overpotentials of -30 and -185 mV with a Tafel slope of 41 mV dec(-1). A controlled potential electrolysis experiment demonstrates that the as-prepared Ni-Co-P film is an efficient and robust catalyst with a faradaic efficiency close to 100%. Systematic characterization suggests that the unique hierarchical structure and the mutual participation of nano-sized Ni/Co based components are responsible for the high HER catalytic activity.
|
|
| 3. |
- Zhang, Wei, et al.
(författare)
-
The Central Role of Ligand Conjugation for Properties of Coordination Complexes as Hole-Transport Materials in Perovskite Solar Cells
- 2019
-
Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 2:9, s. 6768-6779
-
Tidskriftsartikel (refereegranskat)abstract
- Two zinc-based coordination complexes Y3 and Y4 have been synthesized and characterized, and their performance as hole-transport materials (HTMs) for perovskite solar cells (PSCs) has been investigated. The complex Y3 contains two separate ligands, and the molecular structure can be seen as a disconnected porphyrin ring. On the other hand, Y4 consists of a porphyrin core and therefore is a more extended conjugated system as compared to Y3. The optical and redox properties of the two different molecular complexes are comparable. However, the hole mobility and conductivity of Y4 as macroscopic material are remarkably higher than that of Y3. Furthermore, when employed as hole-transport materials in perovskite solar cells, cells containing Y4 show a power conversion efficiency (PCE) of 16.05%, comparable to the Spiro-OMeTAD-based solar cells with an efficiency around 17.08%. In contrast, solar cells based on Y3 show a negligible efficiency of about 0.01%. The difference in performance of Y3 and Y4 is analyzed and can be attributed to the difference in packing of the nonplanar and planar building blocks in the corresponding materials.
|
|
| 4. |
- Cheng, Ming, et al.
(författare)
-
A novel phenoxazine-based hole transport material for efficient perovskite solar cell
- 2015
-
Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier. - 2056-9386. ; 24:6, s. 698-706
-
Tidskriftsartikel (refereegranskat)abstract
- Based on the previous research work in our laboratory, we have designed and synthesized a small-molecule, hole transport material (HTM) POZ6-2 using phenoxazine (POZ) as central unit and dicyanovinyl units as electron-withdrawing terminal groups. Through the introduction of a 2-ethyl-hexyl bulky chain into the POZ core unit, POZ6-2 exhibits good solubility in organic solvents. In addition, POZ6-2 possesses appropriate energy levels in combination with a high hole mobility and conductivity in its pristine form. Therefore, it can readily be used as a dopant-free HTM in perovskite solar cells (PSCs) and a conversion efficiency of 10.3% was obtained. The conductivity of the POZ6-2 layer can be markedly enhanced via doping in combination with typical additives, such as 4-tert-butylpyridine (TBP) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). Correspondingly, the efficiency of the PSCs was further improved to 12.3% using doping strategies. Under the same conditions, reference devices based on the well-known HTM Spiro-OMeTAD show an efficiency of 12.8%.
|
|
| 5. |
- Cheng, Ming, et al.
(författare)
-
Acceptor Donor Acceptor type ionic molecule materials for efficient perovskite solar cells and organic solar cells
- 2016
-
Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855. ; 30, s. 387-397
-
Tidskriftsartikel (refereegranskat)abstract
- Perovskite solar cells (PSCs) have attracted significant interest and hole transporting materials (HTMs) play important roles in achieving high efficiency. Here, we report additive free ionic type HTMs that are based on 2-ethylhexyloxy substituted benzodithiophene (BDT) core unit. With the ionization of end-capping pyridine units, the hole mobility and conductivity of molecular materials are greatly improved. Applied in PSCs, ionic molecular material M7-TFSI exhibits the highest efficiency of 17.4% in the absence of additives [lithium bis(trifluor-omethanesulfonyl)imide and 4-tert-butylpyridine]. The high efficiency is attributed to a deep highest occupied molecular orbital (HOMO) energy level, high hole mobility and high conductivity of M7-TFSI. Moreover, due to the higher hydrophobicity of M7-TFSI, the corresponding PSCs showed better stability than that of Spiro-OMeTAD based ones. In addition, the strong absorption and suitable energy levels of materials (M6, M7-13r and M7-TFSI) also qualify them as donor materials in organic solar cells (OSCs) and the devices containing M7-TFSI as donor material displayed an efficiency of 6.9%.
|
|
| 6. |
- Cheng, Ming, et al.
(författare)
-
Highly Efficient Integrated Perovskite Solar Cells Containing a Small Molecule-PC70BM Bulk Heterojunction Layer with an Extended Photovoltaic Response Up to 900 nm
- 2016
-
Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 28:23, s. 8631-8639
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a high efficiency perovskite solar cell (PSC) integrated with a bulk heterojunction layer, based on acceptor-donor-acceptor (A-D-A) type hole transport material (HTM) and PC70BM composite, yielding improved photoresponse. Two A-D-A-structured hole transporting materials termed M3 and M4 were designed and synthesized. Applied as HTMs in PSCs, power conversion efficiencies (PCEs) of 14.8% and 12.3% were obtained with M3 and M4, respectively. The HTMs M3 and M4 show competitive absorption, but do not contribute to photocurrent, resulting in low current density. This issue was solved by mixing the HTMs with PC70BM to form a bulk heterojunction (BHJ) layer and integrating this layer into the PSC as hole transport layer (HTL). Through careful interface optimization, the (FAPbI(3))(0.85)(MAPbBr(3))(0.15)/HTM:PC70BM integrated devices showed improved efficiencies of 16.2% and 15.0%, respectively. More importantly, the incident-photon-to-current conversion efficiency (IPCE) spectrum shows that the photoresponse is extended to 900 nm by integrating the M4:PC70BM based BHJ and (FAPbI(3))(0.85)(MAPbBr(3))(0.15) layers.
|
|
| 7. |
- Cheng, Ming, et al.
(författare)
-
Phenoxazine-based small molecule material for efficient perovskite solar cells and bulk heterojunction organic solar cells
- 2015
-
Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 5:8
-
Tidskriftsartikel (refereegranskat)abstract
- The phenoxazine-based acceptor-donor-acceptor structured small-molecule material M1 is used either as a hole-transport material in (CH3NH3)PbI3-perovskite-based solar cells or as photoactive donor material in bulk heterojunction organic solar cells. Excellent power conversion efficiencies of 13.2% and 6.9% are achieved in these two types of photovoltaic devices, respectively.
|
|
| 8. |
- Cheng, Minglun, et al.
(författare)
-
Photocatalytic H-2 production using a hybrid assembly of an [FeFe]-hydrogenase model and CdSe quantum dot linked through a thiolato-functionalized cyclodextrin
- 2017
-
Ingår i: Faraday discussions. - : Royal Society of Chemistry. - 1359-6640 .- 1364-5498. ; 198, s. 197-209
-
Tidskriftsartikel (refereegranskat)abstract
- It is a great challenge to develop iron-based highly-efficient and durable catalytic systems for the hydrogen evolution reaction (HER) by understanding and learning from [FeFe]-hydrogenases. Here we report photocatalytic H-2 production by a hybrid assembly of a sulfonate-functionalized [FeFe]-hydrogenase mimic (1) and CdSe quantum dot (QD), which is denoted as 1/beta-CD-6-S-CdSe (beta-CD-6-SH = 6-mercapto-beta-cyclodextrin). In this assembly, thiolato-functionalized beta-CD acts not only as a stabilizing reagent of CdSe QDs but also as a host compound for the diiron catalyst, so as to confine CdSe QDs to the space near the site of diiron catalyst. In addition, another two reference systems comprising MAA-CdSe QDs (HMAA = mercaptoacetic acid) and 1 in the presence and absence of beta-CD, denoted as 1/beta-CD/MAA-CdSe and 1/MAA-CdSe, were studied for photocatalytic H-2 evolution. The influences of beta-CD and the stabilizing reagent beta-CD-6-S- on the stability of diiron catalyst, the fluorescence lifetime of CdSe QDs, the apparent electron transfer rate, and the photocatalytic H-2-evolving efficiency were explored by comparative studies of the three hybrid systems. The 1/beta-CD-6-SCdSe system displayed a faster apparent rate for electron transfer from CdSe QDs to the diiron catalyst compared to that observed for MAA-CdSe-based systems. The total TON for visible-light driven H-2 evolution by the 1/beta-CD-6-S-CdSe QDs in water at pH 4.5 is about 2370, corresponding to a TOF of 150 h(-1) in the initial 10 h of illumination, which is 2.7- and 6.6-fold more than the amount of H-2 produced from the reference systems 1/beta-CD/MAA-CdSe and 1/MAA-CdSe. Additionally, 1/beta-CD-6-S-CdSe gave 2.4-5.1 fold enhancement in the apparent quantum yield and significantly improved the stability of the system for photocatalytic H-2 evolution.
|
|
| 9. |
- Han, Kai, et al.
(författare)
-
Photochemical hydrogen production from water catalyzed by CdTe quantum dots/molecular cobalt catalyst hybrid systems
- 2015
-
Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 51:32, s. 7008-7011
-
Tidskriftsartikel (refereegranskat)abstract
- A hybrid system with a coordinative interaction between a cobalt complex of a N2S2-tetradentate ligand and CdTe quantum dots displayed a high activity (initial TOF 850 h(-1)) and improved stability (TON 1.44 x 10(4) based on catalyst over 30 h) for the photochemical H-2 generation from water, with a quantum efficiency of 5.32% at 400 nm.
|
|
| 10. |
- Hua, Yong, et al.
(författare)
-
Facile synthesis of fluorene-based hole transport materials for highly efficient perovskite solar cells and solid-state dye-sensitized solar cells
- 2016
-
Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 26, s. 108-113
-
Tidskriftsartikel (refereegranskat)abstract
- Two novel low-cost fluorene-based hole transport materials (HTMs) HT1 and HT2 as alternatives to the expensive HTM Spiro-OMeTAD have been designed and synthesized for the application in perovskite solar cells (PSCs) and solid-state dye-sensitized solar cell (ssDSCs). The two HTMs were prepared through a facile two-step reaction from cheap starting material and with a total yield higher than 90%. These HTMs exhibit good solubility and charge-transport ability. PSCs based on HT2 achieved power conversion efficiency (PCE) of 18.04% under air conditions, which is comparable to that of the cell employing the commonly used Spiro-OMeTAD (18.27%), while HT1-based cell showed a slightly worse performance with a PCE of 17.18%. For ssDSCs, the HT2-based device yielded a PCE of 6.35%, which is also comparable to that of a cell fabricated based on Spiro-OMeTAD (6.36%). We found that the larger dimensional structure and molecular weight of HT2 enable better photovoltaic performance than that of the smaller one HT1. These results show that easily synthesized fluorene-based HTMs have great potential to replace the expensive Spiro-OMeTAD for both PSCs and ssDSCs.
|
|
