DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Cu2ZnSnS4 solar cells with over 10% power conversion efficiency enabled by heterojunction heat treatment

Journal Article · · Nature Energy

Sulfide kesterite Cu2ZnSnS4 provides an attractive low-cost, environmentally benign and stable photovoltaic material, yet the record power conversion efficiency for such solar cells has been stagnant at around 9% for years. Severe non-radiative recombination within the heterojunction region is a major cause limiting voltage output and overall performance. Here we report a certified 11% efficiency Cu2ZnSnS4 solar cell with a high 730 mV open-circuit voltage using heat treatment to reduce heterojunction recombination. This heat treatment facilitates elemental inter-diffusion, directly inducing Cd atoms to occupy Zn or Cu lattice sites, and promotes Na accumulation accompanied by local Cu deficiency within the heterojunction region. Consequently, new phases are formed near the hetero-interface and more favourable conduction band alignment is obtained, contributing to reduced non-radiative recombination. Using this approach, we also demonstrate a certified centimetre-scale (1.11 cm2) 10% efficiency Cu2ZnSnS4 photovoltaic device; the first kesterite cell (including selenium-containing) of standard centimetre-size to exceed 10%.

Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Grant/Contract Number:
AC36-08GO28308
OSTI ID:
1466563
Report Number(s):
NREL/JA-5K00-72245
Journal Information:
Nature Energy, Vol. 3, Issue 9; ISSN 2058-7546
Publisher:
Nature Publishing GroupCopyright Statement
Country of Publication:
United States
Language:
English

References (47)

Thin film solar cell with 8.4% power conversion efficiency using an earth-abundant Cu 2 ZnSnS 4 absorber : Cu journal November 2011
Novel five-state latch using double-peak negative differential resistance and standard ternary inverter journal March 2016
Optimization of post-deposition annealing in Cu 2 ZnSnS 4 thin film solar cells and its impact on device performance journal October 2017
Beyond 8% ultrathin kesterite Cu2ZnSnS4 solar cells by interface reaction route controlling and self-organized nanopattern at the back contact journal July 2017
High efficiency thin-film CuIn1−xGaxSe2 photovoltaic cells using a Cd1−xZnxS buffer layer journal December 2006
Atom-probe tomographic study of interfaces of Cu 2 ZnSnS 4 photovoltaic cells journal September 2014
Structure and Composition of Zn x Cd 1– x S Films Synthesized through Chemical Bath Deposition journal June 2012
Effects of heavy alkali elements in Cu(In,Ga)Se 2 solar cells with efficiencies up to 22.6% journal July 2016
Over 9% Efficient Kesterite Cu 2 ZnSnS 4 Solar Cell Fabricated by Using Zn 1- x Cd x S Buffer Layer journal April 2016
Band tailing and efficiency limitation in kesterite solar cells journal September 2013
Carrier Generation and Recombination in P-N Junctions and P-N Junction Characteristics journal September 1957
Impact of Na Dynamics at the Cu 2 ZnSn(S,Se) 4 /CdS Interface During Post Low Temperature Treatment of Absorbers journal February 2016
Photovoltaic materials: Present efficiencies and future challenges journal April 2016
Reduced interface recombination in Cu 2 ZnSnS 4 solar cells with atomic layer deposition Zn 1− x Sn x O y buffer layers journal December 2015
Modelling the effects of distributed series resistance on Suns-Voc, m-Voc and Jsc-Suns curves of solar cells conference June 2009
New World-Record Efficiency for Pure-Sulfide Cu(In,Ga)S 2 Thin-Film Solar Cell With Cd-Free Buffer Layer via KCN-Free Process journal May 2016
Defect Engineering in Multinary Earth-Abundant Chalcogenide Photovoltaic Materials journal January 2017
Effects of sodium incorporation in Co-evaporated Cu 2 ZnSnSe 4 thin-film solar cells journal April 2013
Effects of heavy alkali elements in Cu(In,Ga)Se2 solar cells with efficiencies up to 22.6% text January 2016
Interfacial energy level alignments between low-band-gap polymer PTB7 and indium zinc oxide anode journal August 2015
Valence band offset at the CdS/Cu 2 ZnSnS 4 interface probed by x-ray photoelectron spectroscopy journal April 2013
Incoherent imaging using dynamically scattered coherent electrons journal June 1999
Theoretical analysis of the effect of conduction band offset of window/CIS layers on performance of CIS solar cells using device simulation journal March 2001
Why are kesterite solar cells not 20% efficient? journal May 2013
Effects of Back Contact Instability on Cu 2 ZnSnS 4 Devices and Processes journal July 2013
Rear Surface Optimization of CZTS Solar Cells by Use of a Passivation Layer With Nanosized Point Openings journal January 2016
Sodium Passivation of the Grain Boundaries in CuInSe 2 and Cu 2 ZnSnS 4 for High-Efficiency Solar Cells journal December 2016
Solar cell efficiency tables (version 49): Solar cell efficiency tables (version 49) journal November 2016
Solar cell efficiency tables (version 51)
  • Green, Martin A.; Hishikawa, Yoshihiro; Dunlop, Ewan D.
  • Progress in Photovoltaics: Research and Applications, Vol. 26, Issue 1 https://doi.org/10.1002/pip.2978
journal December 2017
Beyond 11% Efficiency: Characteristics of State-of-the-Art Cu 2 ZnSn(S,Se) 4 Solar Cells journal August 2012
The path towards a high-performance solution-processed kesterite solar cell journal June 2011
Device characteristics of high performance Cu2ZnSnS4 solar cell conference June 2012
Zinc-Tin-Oxide Buffer Layer and Low Temperature Post Annealing Resulting in a 9.0% Efficient Cd-Free Cu 2 ZnSnS 4 Solar Cell journal April 2017
Commercial progress and challenges for photovoltaics journal January 2016
Impact of annealing treatment before buffer layer deposition on Cu 2 ZnSn(S,Se) 4 solar cells journal May 2015
What is the band alignment of Cu 2 ZnSn(S,Se) 4 solar cells? journal September 2017
Fine-Tuning the Sn Content in CZTSSe Thin Films to Achieve 10.8% Solar Cell Efficiency from Spray-Deposited Water-Ethanol-Based Colloidal Inks journal October 2015
Nanoscale Microstructure and Chemistry of Cu 2 ZnSnS 4 /CdS Interface in Kesterite Cu 2 ZnSnS 4 Solar Cells journal June 2016
Engineering Solar Cell Absorbers by Exploring the Band Alignment and Defect Disparity: The Case of Cu- and Ag-Based Kesterite Compounds journal October 2015
Potassium-induced surface modification of Cu(In,Ga)Se2 thin films for high-efficiency solar cells journal November 2013
Ultrafast electron transfer in the nanocomposite of the graphene oxide–Au nanocluster with graphene oxide as a donor journal January 2014
Cation Substitution of Solution-Processed Cu 2 ZnSnS 4 Thin Film Solar Cell with over 9% Efficiency journal July 2015
Efficient kesterite solar cells with high open-circuit voltage for applications in powering distributed devices journal November 2017
Cu 2 ZnSnS 4 photovoltaic cell with improved efficiency fabricated by high-temperature annealing after CdS buffer-layer deposition : Cu journal October 2016
Classification of Lattice Defects in the Kesterite Cu 2 ZnSnS 4 and Cu 2 ZnSnSe 4 Earth-Abundant Solar Cell Absorbers journal February 2013
The Consequences of Kesterite Equilibria for Efficient Solar Cells journal March 2011
Beyond 11% Efficient Sulfide Kesterite Cu 2 Zn x Cd 1– x SnS 4 Solar Cell: Effects of Cadmium Alloying journal March 2017

Cited By (51)

Quasiepitaxy Strategy for Efficient Full‐Inorganic Sb 2 S 3 Solar Cells journal April 2019
Effect of deposition temperature on the growth mechanism of chemically prepared CZTGeS thin films journal April 2019
Stability and electronic properties of planar defects in quaternary I 2 -II-IV-VI 4 semiconductors journal October 2018
Suppressed Deep Traps and Bandgap Fluctuations in Cu 2 CdSnS 4 Solar Cells with ≈8% Efficiency journal October 2019
An 8.7% efficiency co-electrodeposited Cu 2 ZnSnS 4 photovoltaic device fabricated via a pressurized post-sulfurization process journal January 2018
Flexible Cu2ZnSn(S,Se)4 solar cells with over 10% efficiency and methods of enlarging the cell area journal July 2019
Investigation of Optimum Mg Doping Content and Annealing Parameters of Cu2MgxZn1−xSnS4 Thin Films for Solar Cells journal June 2019
Cd(Zn, S)Se quaternary thin films for electrochemical photovoltaic cell application journal April 2020
Sputtered single-phase kesterite Cu 2 ZnSnS 4 (CZTS) thin film for photovoltaic applications: Post annealing parameter optimization and property analysis journal January 2020
Modification of Mo Back Contact with MoO 3−x Layer and its Effect to Enhance the Performance of Cu 2 ZnSnS 4 Solar Cells journal October 2018
Doping and alloying of kesterites journal August 2019
Germanium Incorporation in Cu 2 ZnSnS 4 and Formation of a Sn–Ge Gradient journal September 2019
Interfacial engineering to improve Cu 2 ZnSnX 4 (X = S, Se) solar cell efficiency journal September 2019
Cross-Section Analysis of the Composition of Sprayed Cu 2 ZnSnS 4 Thin Films by XPS, EDS, and Multi-Wavelength Raman Spectroscopy journal November 2018
Tailored multifunctional micellar brushes via crystallization-driven growth from a surface journal November 2019
Chemical Dynamics of Back Contact with MoO 3 Interfacial Layer in Kesterite Solar Cells: Microstructure Evolution and Photovoltaic Performance journal July 2019
Flexible Cu2ZnSn(S,Se)4 solar cells with over 10% efficiency and methods of enlarging the cell area journal July 2019
A self-doping strategy to improve the photoelectrochemical performance of Cu 2 ZnSnS 4 nanocrystal films for water splitting journal January 2019
Dynamic interplay of alkali cations and a natural organic binder in the microstructural evolution of Cu 2 ZnSnS 4 thin films prepared from Cu 2 ZnSnS 4 powder-containing inks journal January 2019
Strong Interplay between Sodium and Oxygen in Kesterite Absorbers: Complex Formation, Incorporation, and Tailoring Depth Distributions journal June 2019
Solar cell efficiency tables (version 54) journal June 2019
A review on the numerical modeling of CdS/CZTS-based solar cells journal January 2019
Role of surface microstructure of Mo back contact on alkali atom diffusion and Ga grading in Cu(In,Ga)Se 2 thin film solar cells journal April 2019
Enhanced Electrical Conductivity of Sb 2 S 3 Thin Film via C 60 Modification and Improvement in Solar Cell Efficiency journal February 2019
Solar cell efficiency tables (Version 55)
  • Green, Martin A.; Dunlop, Ewan D.; Hohl‐Ebinger, Jochen
  • Progress in Photovoltaics: Research and Applications, Vol. 28, Issue 1 https://doi.org/10.1002/pip.3228
journal December 2019
Performance enhancement of Cu 2 ZnSn(S,Se)4 solar cell by inserting Sb and Sb 2 Se 3 doping layer at the bottom of CZTS precursor journal December 2019
Physical routes for the synthesis of kesterite journal September 2019
Etching process optimization of non-vacuum fabricated Cu2ZnSnS4 solar cell journal January 2020
Effect of Sb and Na Incorporation in Cu 2 ZnSnS 4 Solar Cells journal April 2019
Solar cell efficiency tables (Version 53)
  • Green, Martin A.; Hishikawa, Yoshihiro; Dunlop, Ewan D.
  • Progress in Photovoltaics: Research and Applications, Vol. 27, Issue 1 https://doi.org/10.1002/pip.3102
journal December 2018
All Solution-Processed Cu 2 ZnSnS 4 Solar Cell by Using High-Boiling-Point Solvent Treated Ball-Milling Process with Efficiency Exceeding 6% journal January 2019
Progress and Perspectives of Thin Film Kesterite Photovoltaic Technology: A Critical Review journal February 2019
Enhanced Hetero‐Junction Quality and Performance of Kesterite Solar Cells by Aluminum Hydroxide Nanolayers and Efficiency Limitation Revealed by Atomic‐resolution Scanning Transmission Electron Microscopy journal December 2018
Effect of solid-H 2 S gas reactions on CZTSSe thin film growth and photovoltaic properties of a 12.62% efficiency device journal January 2019
Flexible high-efficiency CZTSSe solar cells on stainless steel substrates journal January 2019
Preparation and characterization of Cu 2 ZnSnS 4 thin films by two-stage process journal February 2019
Open-circuit voltage deficit in Cu 2 ZnSnS 4 solar cells by interface bandgap narrowing journal November 2018
All‐Layer Sputtering‐Free Cu2Zn1‐xCdxSnS4 Solar Cell with Efficiency Exceeding 7.5% journal May 2019
Enhancing the open-circuit voltage and efficiency of CZTS thin-film solar cells via band-offset engineering journal January 2020
An approach towards the promotion of Kesterite solar cell efficiency: The use of nanostructures journal September 2019
Photo-enhanced supercapacitive behaviour of photoactive Cu2FeSnS4 (CFTS) nanoparticles journal November 2019
Fabrication of Ag and Mn Co-Doped Cu2ZnSnS4 Thin Film journal October 2019
Back-surface recombination, electron reflectors, and paths to 28% efficiency for thin-film photovoltaics: A CdTe case study journal February 2019
Effect of selenization temperature on the formation of CZTSe absorber layer journal November 2019
Cd-Free Cu 2 ZnSnS 4 solar cell with an efficiency greater than 10% enabled by Al 2 O 3 passivation layers journal January 2019
Emerging inorganic solar cell efficiency tables (Version 1) journal July 2019
Aqueous-based Binary Sulfide Nanoparticle Inks for Cu2ZnSnS4 Thin Films Stabilized with Tin(IV) Chalcogenide Complexes journal September 2019
Back and front contacts in kesterite solar cells: state-of-the-art and open questions journal October 2019
7.5% n–i–p Sb 2 Se 3 solar cells with CuSCN as a hole-transport layer journal January 2019
Phase pure CuSbS2 thin films by heat treatment of electrodeposited Sb2S3/Cu layers journal January 2020
Cadmium Free Cu 2 ZnSnS 4 Solar Cells with 9.7% Efficiency journal April 2019