Hard Condensed Matter WZI

Transcription

1 Hard Condensed Matter WZI Tom Gregorkiewicz University of Amsterdam VU-LaserLab Dec 10, 2015

2 Hard Condensed Matter Cluster Quantum Matter Optoelectronic Materials

3 Quantum Matter Amsterdam Mark Golden Anne de Visser Erik van Heumen Ying kai Huang

4 The QMA toolbox Transport STM/STS New materials /Optics Crystal growth Photoemission Optical spectroscopy

5 Advanced materials unconventional superconductivity iron pnictides, UCoGe, topological superconductors correlated oxides & low dimensional systems colossal magnetoresistance in manganites oxide heterointerfaces 1D nanowires on semiconductors topological insulators Create, investigate and control: new materials for future nano-electronics

6 Topological insulators Create Investigate Γ M Improve functionality k-space and r-space microscopy Control theo ry theo ry Golden Lab Simulations

7 Unconventional superconductors Superconducting ferromagnets: UCoGe odd-parity superconductivity mediated by spin-fluctuations Candidate topological superconductors Cu x Bi 2 Se 3, Sr x Bi 2 Se 3 half Heuslers compounds: YPtBi, ErPdBi, HoPdBi upper critical field mixed even and odd parity Cooper pairing coexistence of antiferromagnetism and superconductivity PPMS Heliox Kelvinox de Visser Lab

8 Towards nanoscale control Topological materials as novel optoelectronics platform Devices offer tunability! 20 μμm Towards nano-optics experiments: cleanroom) First TI based devices van Heumen Lab Photocurrent microscope Spin polarized current!

9 Optoelectronic New materials Materials for PV Optical processes for (solar) energy harvesting Fundamental processes limiting conversion efficiency The main problem: continuous character of the solar spectrum vs discrete character of convertor devices

10 WZI-UvA

11 Solar spectral shaping

12 Solar spectral shaping 2.2 ev: twice band gap of silicon Quantum cutting Quantum shifting 1.1 ev: band gap of silicon Quantum pasting

13 why nanocrystals Effective bandgap Band gap [ev] nanocrystal Size - d [nm]

14 photon convertors CB VB

15 photon limiters CB VB

16 photon limiters CB VB Auger

17 photon limiters CB heat generation VB

18 Energy transfer to the outside emitter emitter: RE ion, molecule, color center,

19 Carrier multiplication process For E exc 2E gap 21/73

20 MEG in proximal Si NCs For E exc 2E gap

21

22 Silicon nanocrystals not at all that impressive

23 Perovskite nanocrystals CsPbCl 3 CsPb(Cl/Br) 3 CsPbBr 3 CsPb(Br/I) 3 CsPbI 3

24 SOLARDAM Use of semiconductor nanostructures for spectral conversion Exploration of doped nanocrystals for down- and up conversion Exploration of hot carriers and phonon management in nanocrystals for highly efficient solar energy harvesting and conversion

25 Thank you! WZI-UvA

26 SOLARDAM Use of semiconductor nanostructures for spectral conversion Exploration of doping for down- and up conversion Exploration of hot carriers and phonon management for highly efficient solar energy harvesting solutions

27 Big Issues in Energy Materials

28 Efficiency New materials considerations for PV Fundamental limits Technical limits The main problem: continuous character of the solar spectrum vs discrete character of a conversion device

29 UvA

30 PV conversion loses X ~33% X ~19%

31 Shockley-Queisser limit

32 Tandem cell concept

33 Efficiency considerations The main problem: continuous character of solar spectrum and discrete character of PV devices Solution: change solar spectrum photon shifting, cutting and pasting monowavelength conversion SOLAR SHAPERS

34 Up-conversion of photons 2 photons of energy 0.5 E g < hν< E g are converted to 1 photon of hν> E g 11/80

35 Down-conversion of photons 1 photon of energy hν > 2E g is converted into 2 photons of hν > E g 12/80

36 Solar shapers 13/80

37 Efficiency considerations The quantum efficiency of a Si solar cell 14/80

38 Emission nanostructures 2) Bandgap opening effect (Strong effect in quantum dots) 2 nπ E( n) = 2m L Particle in a box 2 CdSe QDs [Bera et al. 2009] 30/80

39 QD artificial atom Atom Quantum dot Bulk semiconductor e - h + Energy kt λ λ λ 36/80

40 Inorganic perovskites NCs Cesium Lead Halide Perovskites (CsPbX 3, X = Cl, Br, I) L. Protesescu et al., Nano Letters 2015, 15, /80

41 Si Nanocrystals in SiO 2 Paillard et al., Tolouse 57/80

42 Effect of doping 64/80

43 Emergent Energy Materials

44 Silicon nanocrystals not at all that impressive 66/80

45 Si NC photoluminescence SiNC PL CB VB 75/80

46 Si NC PL saturation Poissonian simulation shows saturation of PL intensity for situation of N exc 1 PL decay independent of pump power 80/80

47 Probing RET: samples Multilayer approach 1) Less neighbors (2D RET confinement) 2) Larger first-neighbor distance RET rate should be quenched 49/52 5/73

48 Carrier Multiplication NCs For E exc 2E gap CM fast component in carrier lifetime dynamics 23/73

49 37/73

50 CM efficiency IA (this work) PL efficiency (Ref. 33) Limit by energy conservation E exc /E g Exciton vs carrier generation 38/73

51 Energy recycling in Si NCs MEG Auger energy recycling Conspiracy of impact excitation and Auger recombination operating in parallel 48/73

52 Energy recycling in Si NCs Phonon confinement inside NCs influences transition probabilities 53/73

53 Effect phonon-enhancement τ radiative (µs) >> τ Auger (ps) 58/73

54 Energy recycling in Si NCs MEG Auger energy recycling Can we use the excess energy of hot carriers? 60/73

55 71/73

56 Hot carriers in doped NCs 72/73

57 Hot carriers for spectral conversion New opportunities for doped Si nanocrystals? 73/73

58 Thank you! UvA