1. Depleted heterojunction solar cells. 2. Deposition of semiconductor layers with solution process. June 7, Yonghui Lee

Transcription

1 1. Depleted heterojunction solar cells 2. Deposition of semiconductor layers with solution process June 7, 2016 Yonghui Lee

2 Outline 1. Solar cells - P-N junction solar cell - Schottky barrier solar cell - DSC (or QDSC) - Depleted heterojunction solar cell - Energy level alignment - Funnel structure 2. Deposition of semiconductor layers by solution method - Spray pyrolysis deposition for CdS - Successive ionic layer adsorption and reaction for CdSe - Chemical bath deposition for Sb 2 S 3 - Spin-coating deposition using single source precursor for Sb 2 Se 3

3 Solar cells Electron-hole pair generation Solar cell How to collect such electrons and holes?

4 Potential Energy

5 Silicon p-n junction solar cell

6 Depleted heterojunction solar cell ACS Nano, 2010, 4,

7 Energy level alignment of TiO 2 and CQDs Colloidal quantum dots ACS Nano 2010, 4, 3374.

8 Energy level alignment of TiO 2 and CQDs Chem. Rev. 2014, 114, 863.

9 CQD solar cells using quantum funnels Nano Lett. 2011, 11, 3701.

10 Back surface field (BSF)

11 Hole transport materials (HTM) 1. FTO/TiO 2 (n)/cdte(p)/au 2. FTO/TiO 2 (n)/cdte(p)/p3ht/au FTO -4.7 FTO -4.2 TiO2 3.2 e CdTe Au h + FTO -4.7 FTO -4.2 TiO2 3.2 e CdTe e P3HT h + Au h + Au TiO 2 CdTe(p) Au -7.4 TiO 2 CdTe(p) P3HT -7.4 Without HTM With HTM

12 Deposition of semiconductor layers with solution process E (ev) -4.2 TiO CdS CdSe Sb2S MoS PbS Cu2S MAPbI CdTe P3HT CIGS CIS

13 1. CdS by spray pyrolysis deposition (SPD) 2. CdSe by successive ionic layer adsorption and deposition (SILAR) 3. Sb 2 S 3 by chemical bath deposition (CBD) 4. Sb 2 Se 3 by spin-coating of single-source precursors (SSP)

14 CdS by spray pyrolysis deposition (a) air Selective etching mp-tio 2 of CdCl 2 bl-tio 2 FTO Glass CdS CdCl 2 Glass (b) (c) Washing with water

15 XRD analysis CdCl 2 : JCPDS ( ) CdCl 2 =0.15M/Washed Intensity (a.u.) CdCl 2 = 0.15M CdCl 2 = 0.1M CdCl 2 = 0.05M θ (dergee) X-ray diffraction (XRD) patterns of film deposited on glass substrate

16 CdS by spray pyrolysis deposition; Surface morphology engineering by successive oxidation and etching Oxidation by thermal annealing Etching by HCl CdS CdO

17 XRD analysis As-deposited Oxidation HCl etching Intensity (a. u.) CdS CdO θ (degree) X-ray diffraction patterns of as-deposited, oxidized and oxidized/hcl treated CdS deposited on a bare glass

18 (a) TEM images (b) CdS TiO 2 TEM images of (a) as-deposited CdS on mp-tio 2 and (b) reconstructed CdS on mp-tio 2 by thermal annealing and etching

19 J-V curves, EQE measurement Current density (ma/cm 2 ) (a) sample Jsc (ma/cm 2 ) Voc (mv) FF (%) η (%) As-dep Oxid Oxid./HCl As-deposited Oxidation Oxidation/HCl EQE (%) (b) As-deposited Oxidation Oxidation/HCl Transmittance (a.u.) Voltage (V) Wavelength(nm) Device characterization of CdS-SSC in I /I 3 electrolyte system. (a) J-V curves and (b) EQE and UV-Visible transmittance of as-deposited (black solid line) and thermally oxidized (red solid line) CdS/mp-TiO 2 film

20 Successive Ionic Layer Adsorption and Reaction (SILAR) (a) TiO 2 e - h + e h + Molecular dipole CdSe P3HT Au CdSe by SILAR: 0.03 M Cd(NO 3 ) 2, 0.03 M Se 2- in EtOH, glove bag under N 2 (a) Schematic illustration of energy band diagram of CdSe-sensitized heterojunction solar cell, (b) cross-sectional SEM image, and (c) TEM image of CdSe deposited on mesoscopic TiO 2 electrode (b) Au (c) P3HT /CdSe/ TiO 2 bl-tio 2 FTO 500 nm 500 nm 50 nm 50 nm Organ. Electron. 2012, 13, 975.

21 T (%) (a) CdSe-10 CdSe-8 CdSe-12 (a) UV-Visible transmission spectra of CdSe deposited on mesoscopic TiO 2 film according to the number of SILAR cycles: inset = photograph, (b) J-V curves, and (c) EQE spectra of CdSe-sensitized heterojunction solar cells 20 J (ma/cm 2 ) EQE (%) Wavelength (nm) CdSe-8 CdSe-10 CdSe Voltage (V) (b) (c) CdSe-8 CdSe-10 CdSe Wavelength (nm) The table summarizing device performance with the number of SILAR cycles J sc (ma/cm 2 ) V oc (V) FF (%) η (%) CdSe CdSe CdSe

22 Sb 2 S 3 sensitized solar cells Nano Lett. 2010, 10, 2609.

23 Chemical bath deposition (CBD) of Sb 2 S 3 TiO 2 electrode As-prepared a-sb 2 S 3 films Au counter electrode c-sb 2 S 3 after annealing Measurement Deposition of HTM

24 Deposition of Sb 2 Se 3 using a single source precursor (SSP) Angew.Chem.Int.Ed. 2013, 52, 1.

25 500 Intensity (a. u.) After annealing, 300 o C/10 m, N 2 * Sb 2 Se 3 (PDF# ) θ (degree)

26 Deposition of Sb 2 (S x Se 1-x ) 3 graded-composition sensitizer Adv. Energy Mater. 2014, 4,