Showing posts with label review. Show all posts
Showing posts with label review. Show all posts

May 23, 2019

Paper: Kesterite solar cell with 12.6% efficiency

Cited 1900 times (May 2019) -  Journal: Advanced Energy Materials
Link: Device Characteristics of CZTSSe Thin-Film Solar Cells with 12.6% Efficiency 

Challenge:

Decrease Voc deficit of current CZTSSe (1.13 eV) solar cells.

The reported device has 12.6 % efficiency with  500 mV of Voc from a maximum of 820 mV calculated by SQ analysis. Therefore if Voc is enhanced the device would get better. But to achieve this enhancement we should understand the dependence between minority carrier lifetime and recombination process.

Highlights:

  • Kesterites are fabricated with Cu-poor and Zn-rich content
  • Understand:  junction CdS/CZTSSe, current collection and recombination mechanism
  • Defects impact the minority carrier lifetime and thus collection length (Lc = Xp + Ln). 
  • Lifetime (µn, µp, defects)  
Characterization Techniques:

  • SIMS - Analysis of carbon and oxygen concentration 
  • SEM - Morphology (Front and cross section)
  • EDX - Composition (Cu, Zn, Sn) profiling 
  • JV - Basic parameters (Voc, Jsc, FF, Eff) 
  • Sites method: Diode parameter - Ideality factor, Saturation current Jo, Rs, Rsh
  • CV - Concentration and nature of defects: Sensitive to interface traps
  • DLCP - (Drive level capacitance profile): Sensitive to bulk defects
  • JVT - Activation energy of the main recombination process
  • EQE - External quantum efficiency: Eg 
  • UV-VIS-NIR: Optical reflectance
  • EBIC - Indicate collection region for minority carriers. 
Device fabrication:

  • CZTSSe fabricate by pure-solution method (Hydrazine)
  • Back contact: Molybdenum (500 nm) 
  • Mo(S,Se)2:  approx (180 nm)
  • Absorber: CZTSSe (2 µm)
  • Buffer: CdS (25 nm)
  • Window: ZnO/ITO (10 nm / 50 nm)
  • Grid: Ni/Al (2 µm)
  • Anti-reflective: MgF2
  • Total area: 0.42 cm2 defined by mechanic scribe

April 22, 2019

Review of the STARCELL project publications

 This project is developed in the European Union due to photovoltaics is one of the main technologies necessary to achieve the targets of EU Energy Roadmap 2050.  For me, it is interesting to know the state of the art of this material as a prospect for a postdoctoral stay in 2019-2020.

  • This topic is highly related to solar cell development and innovation.
  • One key feature is the development of thin film photovoltaics using flexible substrates



Webpage Snapshot (April 22nd, 2019) - STARCELL Project 

STARCELL aims to substitute two critical raw materials (In and Ga) used in conventional thin film photovoltaic (PV) technologies, via the introduction of sustainable kesterite (Cu
2ZnSn(S,Se)4 - CZTSSe) semiconductors. (Project STARCELL Objective)

Publications:


[1] S. Giraldo, E. Saucedo, M. Neuschitzer, F. Oliva, M. Placidi, X. Alcobé, V. Izquierdo-Roca, S. Kim, H. Tampo, H. Shibata, A. Pérez-Rodríguez, P. Pistor, How small amounts of Ge modify the formation pathways and crystallization of kesterites, Energy Environ. Sci. 11 (2018) 582–593. doi:10.1039/c7ee02318a. (Link)(Cited by 22)

[2] S.G. Haass, C. Andres, R. Figi, C. Schreiner, M. Bürki, Y.E. Romanyuk, A.N. Tiwari, Complex Interplay between Absorber Composition and Alkali Doping in High-Efficiency Kesterite Solar Cells, Adv. Energy Mater. 8 (2018) 1–9. doi:10.1002/aenm.201701760. (Link) (Cited by 11)


[3] C.J. Hages, A. Redinger, S. Levcenko, H. Hempel, M.J. Koeper, R. Agrawal, D. Greiner, C.A. Kaufmann, T. Unold, Identifying the Real Minority Carrier Lifetime in Nonideal Semiconductors: A Case Study of Kesterite Materials, Adv. Energy Mater. 7 (2017) 1–10. doi:10.1002/aenm.201700167. (Link) (Cited by )


[4] J. Márquez, H. Stange, C.J. Hages, N. Schaefer, S. Levcenko, S. Giraldo, E. Saucedo, K. Schwarzburg, D. Abou-Ras, A. Redinger, M. Klaus, C. Genzel, T. Unold, R. Mainz, Chemistry and Dynamics of Ge in Kesterite: Toward Band-Gap-Graded Absorbers, Chem. Mater. 29 (2017) 9399–9406. doi:10.1021/acs.chemmater.7b03416. (Link