{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T05:03:22Z","timestamp":1784178202861,"version":"3.55.0"},"reference-count":62,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T00:00:00Z","timestamp":1783641600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Science and Technology Council, Taiwan","award":["109-2622-E-006-038 and 114-2221-E-006-128"],"award-info":[{"award-number":["109-2622-E-006-038 and 114-2221-E-006-128"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Colloidal processing provides a scalable non-vacuum route for fabricating CIGS and CZTSSe thin-film absorbers, but nanoparticle-derived films should be treated as constrained particulate green bodies rather than as simple chemically deposited semiconductor layers. This review reorganizes colloidal chalcogenide photovoltaics using ceramic-processing concepts: ink dispersion, green-body packing, capillary drying stress, ligand burnout, constrained shrinkage, reactive chalcogenization, transient liquid-assisted coarsening, secondary-phase control, defect chemistry, and interface reactions. The central argument is that film densification and grain growth are necessary but insufficient for high-performance CZTSSe devices. Residual carbon, Sn loss, Cu\/Zn disorder, ZnSe or Cu2\u2212xSe secondary phases, excessive MoSe2, and nonideal absorber\/buffer band alignment can dominate open-circuit-voltage loss, fill factor, and carrier collection even when the absorber appears dense in cross-sectional microscopy. By linking ceramic-processing variables to photovoltaic loss mechanisms, this review identifies practical routes for improving colloidal chalcogenide solar cells: controlled ligand exchange and binder burnout, high-green-density precursor design, moderated chalcogen chemical potential, transient liquid management, depth-resolved phase analysis, and integrated front\/back-interface engineering.<\/jats:p>","DOI":"10.3390\/ma19142989","type":"journal-article","created":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T14:14:25Z","timestamp":1783692865000},"page":"2989","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Ceramic-Processing Perspectives on Colloidal CIGS and CZTSSe Thin-Film Solar Absorbers: Green-Body Formation, Reactive Chalcogenization, and Defect Engineering"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7058-218X","authenticated-orcid":false,"given":"Hsing-I.","family":"Hsiang","sequence":"first","affiliation":[{"name":"Department of Resources Engineering, National Cheng Kung University, Tainan 70101, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,10]]},"reference":[{"key":"ref_1","unstructured":"National Renewable Energy Laboratory (2026, May 10). Best Research-Cell Efficiencies Chart, Rev, Available online: https:\/\/www.nrel.gov\/pv\/cell-efficiency.html."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"795","DOI":"10.1002\/pip.3919","article-title":"Solar cell efficiency tables (version 66)","volume":"33","author":"Green","year":"2025","journal-title":"Prog. Photovolt. Res. Appl."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"042502","DOI":"10.1088\/2399-1984\/ae0fee","article-title":"High efficiency III-V nanowire solar cells: The road ahead","volume":"9","author":"Prete","year":"2025","journal-title":"Nano Futur."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"18149","DOI":"10.1021\/acsanm.2c04044","article-title":"Enhanced optical absorption of GaAs near-band-edge transitions in GaAs\/AlGaAs core-shell nanowires: Implications for nanowire solar cells","volume":"5","author":"Prete","year":"2022","journal-title":"ACS Appl. Nano Mater."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"467","DOI":"10.1038\/s41560-024-01472-3","article-title":"High-concentration silver alloying and steep back-contact gallium grading enabling copper indium gallium selenide solar cell with 23.6% efficiency","volume":"9","author":"Keller","year":"2024","journal-title":"Nat. Energy"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"E156","DOI":"10.1002\/adma.200904155","article-title":"High-efficiency solar cell with earth-abundant liquid-processed absorber","volume":"22","author":"Todorov","year":"2010","journal-title":"Adv. Mater."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1522","DOI":"10.1002\/adma.201203146","article-title":"Classification of lattice defects in the kesterite Cu2ZnSnS4 and Cu2ZnSnSe4 earth-abundant solar cell absorbers","volume":"25","author":"Chen","year":"2013","journal-title":"Adv. Mater."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1002\/aenm.201100630","article-title":"Kesterite thin-film solar cells: Advances in materials modelling of Cu2ZnSnS4","volume":"2","author":"Walsh","year":"2012","journal-title":"Adv. Energy Mater."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"20110432","DOI":"10.1098\/rsta.2011.0432","article-title":"Prospects and performance limitations for Cu-Zn-Sn-S-Se photovoltaic technology","volume":"371","author":"Mitzi","year":"2013","journal-title":"Philos. Trans. R. Soc. A"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"3030","DOI":"10.1111\/j.1551-2916.2011.04488.x","article-title":"Formation mechanisms of Cu(In0.7Ga0.3)Se2 nanocrystallites synthesized using hot-injection and heating-up processes","volume":"94","author":"Hsu","year":"2011","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.jssc.2013.09.033","article-title":"Controlling morphology and crystallite size of Cu(In0.7Ga0.3)Se2 nanocrystals synthesized using a heating-up method","volume":"208","author":"Hsu","year":"2013","journal-title":"J. Solid State Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3208","DOI":"10.1016\/j.ceramint.2014.10.179","article-title":"Crystallite formation mechanism of CuIn(Se,S)2 synthesized using solvothermal method","volume":"41","author":"Hsiang","year":"2015","journal-title":"Ceram. Int."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"99297","DOI":"10.1039\/C6RA20692A","article-title":"Characterization of CuSbSe2 crystallites synthesized using a hot-injection method","volume":"6","author":"Hsiang","year":"2016","journal-title":"RSC Adv."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"6950","DOI":"10.1016\/j.jallcom.2011.04.009","article-title":"CuInSe2 nano-crystallite reaction kinetics using solid-state reaction from Cu2Se and In2Se3 powders","volume":"509","author":"Hsiang","year":"2011","journal-title":"J. Alloys Compd."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"3141","DOI":"10.1002\/adma.200802027","article-title":"Solution processing of chalcogenide semiconductors via dimensional reduction","volume":"21","author":"Mitzi","year":"2009","journal-title":"Adv. Mater."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2393","DOI":"10.1016\/0001-6160(88)90189-7","article-title":"On constrained sintering-I. Constitutive model for a sintering body","volume":"36","author":"Bordia","year":"1988","journal-title":"Acta Metall."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1637","DOI":"10.1111\/j.1551-2916.2007.01572.x","article-title":"Effect of constrained sintering on microstructure evolution","volume":"90","author":"Guillon","year":"2007","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2341","DOI":"10.1111\/j.1151-2916.2000.tb01560.x","article-title":"Colloidal processing of ceramics","volume":"83","author":"Lewis","year":"2000","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Richerson, D.W., and Lee, W.E. (2018). Modern Ceramic Engineering: Properties, Processing, and Use in Design, CRC Press. [4th ed.].","DOI":"10.1201\/9780429488245"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1111\/j.1151-2916.1990.tb05082.x","article-title":"Theory of drying","volume":"73","author":"Scherer","year":"1990","journal-title":"J. Am. Ceram. Soc."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"836","DOI":"10.1002\/pip.2756","article-title":"The role of nanoparticle inks in determining the performance of solution processed Cu2ZnSn(S,Se)4 thin film solar cells","volume":"24","author":"Qu","year":"2016","journal-title":"Prog. Photovolt. Res. Appl."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"19576","DOI":"10.1039\/D5TA10062C","article-title":"Water-based inks for inkjet-printed Cu(In,Ga)(S,Se)2 thin-film solar cells with a power conversion efficiency of 15%","volume":"14","author":"Liu","year":"2026","journal-title":"J. Mater. Chem. A"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1903173","DOI":"10.1002\/aenm.201903173","article-title":"Effect of Cu-Sn-Se liquid phase on grain growth and efficiency of CZTSSe solar cells","volume":"10","author":"Kim","year":"2020","journal-title":"Adv. Energy Mater."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"6650","DOI":"10.1038\/s41467-023-42460-7","article-title":"Controlling selenization equilibrium enables high-quality kesterite absorbers for efficient solar cells","volume":"14","author":"Xu","year":"2023","journal-title":"Nat. Commun."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"053522","DOI":"10.1063\/1.3691964","article-title":"Existence and removal of Cu2Se second phase in coevaporated Cu2ZnSnSe4 thin films","volume":"111","author":"Tanaka","year":"2012","journal-title":"J. Appl. Phys."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1016\/j.tsf.2012.12.095","article-title":"HCl and Br2-MeOH etching of Cu2ZnSnSe4 polycrystalline absorbers","volume":"535","author":"Mousel","year":"2013","journal-title":"Thin Solid Films"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/j.tsf.2016.09.011","article-title":"Effect of ammonium sulfide treatments on the surface properties of Cu2ZnSnSe4 thin films","volume":"633","author":"Brammertz","year":"2017","journal-title":"Thin Solid Films"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Zaki, M.Y., and Velea, A. (2024). Recent progress and challenges in controlling secondary phases in kesterite CZT(S\/Se) thin films: A critical review. Energies, 17.","DOI":"10.3390\/en17071600"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"167885","DOI":"10.1016\/j.ijleo.2021.167885","article-title":"Numerical analysis of the role of p-MoSe2 interfacial layer in CZTSe thin-film solar cells using SCAPS simulation","volume":"247","author":"Moustafa","year":"2021","journal-title":"Optik"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Chen, C.-Y., Kholimatussadiah, S., Chen, W.-C., Lin, Y.-R., Lin, J.-W., Chen, P.-T., Chen, R.-S., Chen, K.-H., and Chen, L.-C. (2022). Back contact engineering to improve CZTSSe solar cell performance by inserting MoO3 sacrificial nanolayers. Sustainability, 14.","DOI":"10.3390\/su14159511"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Jeong, W.L., Park, S.H., Jho, Y.D., Joo, S.K., and Lee, D.S. (2022). The role of the graphene oxide (GO) and reduced graphene oxide (RGO) intermediate layer in CZTSSe thin-film solar cells. Materials, 15.","DOI":"10.3390\/ma15103419"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1021\/acsaem.9b01732","article-title":"Real-time electron nanoscopy of photovoltaic absorber formation from kesterite nanoparticles","volume":"3","author":"Qu","year":"2020","journal-title":"ACS Appl. Energy Mater."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Jenkins, R., and Snyder, R.L. (1996). Introduction to X-Ray Powder Diffractometry, Wiley.","DOI":"10.1002\/9781118520994"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1148","DOI":"10.1016\/j.apsusc.2017.07.273","article-title":"Different ligand exchange solvents effect on the densification of CuIn0.7Ga0.3Se2 prepared using the heating-up method","volume":"426","author":"Yang","year":"2017","journal-title":"Appl. Surf. Sci."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Jiang, D., Zhang, Y., Sui, Y., He, W., Wang, Z., Yang, L., Wang, F., and Yao, B. (2019). Investigation on the selenization treatment of kesterite Cu2Mg0.2Zn0.8Sn(S,Se)4 films for solar cell. Nanomaterials, 9.","DOI":"10.3390\/nano9070946"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1301465","DOI":"10.1002\/aenm.201301465","article-title":"Device characteristics of CZTSSe thin-film solar cells with 12.6% efficiency","volume":"4","author":"Wang","year":"2014","journal-title":"Adv. Energy Mater."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1501070","DOI":"10.1002\/aenm.201501070","article-title":"Large efficiency improvement in Cu2ZnSnSe4 solar cells by introducing a superficial Ge nanolayer","volume":"5","author":"Giraldo","year":"2015","journal-title":"Adv. Energy Mater."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"14814","DOI":"10.1002\/chem.201302589","article-title":"ZnSe etching of Zn-rich Cu2ZnSnSe4: An oxidation route for improved solar-cell efficiency","volume":"19","author":"Placidi","year":"2013","journal-title":"Chem. Eur. J."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"107299","DOI":"10.1016\/j.mtcomm.2023.107299","article-title":"Effect of In(O,S) buffer layer on the band alignment and the performance of CZT(S,Se) thin-film solar cells","volume":"37","author":"Charghandeh","year":"2023","journal-title":"Mater. Today Commun."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"16770","DOI":"10.1021\/ja805845q","article-title":"Synthesis of CuInS2, CuInSe2, and Cu(InxGa1-x)Se2 nanocrystal inks for printable photovoltaics","volume":"130","author":"Panthani","year":"2008","journal-title":"J. Am. Chem. Soc."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"11672","DOI":"10.1021\/ja904981r","article-title":"Synthesis of Cu2ZnSnS4 nanocrystal ink and its use for solar cells","volume":"131","author":"Guo","year":"2009","journal-title":"J. Am. Chem. Soc."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1002\/pip.1253","article-title":"Solution-processed Cu(In,Ga)(S,Se)2 absorber yielding a 15.2% efficient solar cell","volume":"21","author":"Todorov","year":"2013","journal-title":"Prog. Photovolt. Res. Appl."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"732","DOI":"10.1002\/aenm.201100140","article-title":"Earth-abundant element photovoltaics directly from soluble precursors with high yield using a non-toxic solvent","volume":"1","author":"Ki","year":"2011","journal-title":"Adv. Energy Mater."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"15644","DOI":"10.1021\/ja3057985","article-title":"High-efficiency solution-processed Cu2ZnSn(S,Se)4 thin-film solar cells prepared from binary and ternary nanoparticles","volume":"134","author":"Cao","year":"2012","journal-title":"J. Am. Chem. Soc."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"64","DOI":"10.1002\/pip.2200","article-title":"Ink formulation and low-temperature incorporation of sodium to yield 12% efficient Cu(In,Ga)(S,Se)2 solar cells from sulfide nanocrystal inks","volume":"21","author":"Guo","year":"2013","journal-title":"Prog. Photovolt. Res. Appl."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"1550","DOI":"10.1002\/pip.2588","article-title":"Synthesis and characterization of 15% efficient CIGSSe solar cells from nanoparticle inks","volume":"23","author":"McLeod","year":"2015","journal-title":"Prog. Photovolt. Res. Appl."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"2404669","DOI":"10.1002\/adfm.202404669","article-title":"Li-doping and Ag-alloying interplay shows the pathway for kesterite solar cells with efficiency over 14%","volume":"34","author":"Gong","year":"2024","journal-title":"Adv. Funct. Mater."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"654","DOI":"10.1002\/pip.2472","article-title":"9.0% efficient Cu2ZnSn(S,Se)4 solar cells from selenized nanoparticle inks","volume":"23","author":"Miskin","year":"2015","journal-title":"Prog. Photovolt. Res. Appl."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"33","DOI":"10.2138\/rmg.2014.78.2","article-title":"Fundamentals of XAFS","volume":"78","author":"Newville","year":"2014","journal-title":"Rev. Mineral. Geochem."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"621","DOI":"10.1103\/RevModPhys.72.621","article-title":"Theoretical approaches to x-ray absorption fine structure","volume":"72","author":"Rehr","year":"2000","journal-title":"Rev. Mod. Phys."},{"key":"ref_51","doi-asserted-by":"crossref","unstructured":"Wu, Y., Sui, Y., He, W., Zeng, F., Wang, Z., Wang, F., Yao, B., and Yang, L. (2020). Substitution of Ag for Cu in Cu2ZnSnSe4: Toward wide band gap absorbers with low antisite defects for thin film solar cells. Nanomaterials, 10.","DOI":"10.3390\/nano10010096"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"2305938","DOI":"10.1002\/advs.202305938","article-title":"Unveiling the role of Ge in CZTSSe solar cells by advanced micro-to-atom scale characterizations","volume":"11","author":"Cong","year":"2024","journal-title":"Adv. Sci."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"10260","DOI":"10.1039\/D4TA00133H","article-title":"Defect-level trap optimization in Cu2ZnSn(S,Se)4 photovoltaic materials via Sb3+-doping for over 13% efficiency solar cells","volume":"12","author":"Li","year":"2024","journal-title":"J. Mater. Chem. A"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"2300061","DOI":"10.1002\/solr.202300061","article-title":"Passivation of grain boundaries and defects in CZTSSe solar cells by in situ Na doping","volume":"7","author":"Dong","year":"2023","journal-title":"Sol. RRL"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"135008","DOI":"10.1016\/j.cej.2022.135008","article-title":"Defects passivation and crystal growth promotion by solution-processed K doping strategy toward 16.02% efficiency Cu(In,Ga)(S,Se)2 solar cells","volume":"436","author":"Zhao","year":"2022","journal-title":"Chem. Eng. J."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"3674","DOI":"10.1039\/C6EE02352E","article-title":"High efficiency solution-processed thin-film Cu(In,Ga)(Se,S)2 solar cells","volume":"9","author":"Zhang","year":"2016","journal-title":"Energy Environ. Sci."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"2072","DOI":"10.1021\/es8019534","article-title":"Materials availability expands the opportunity for large-scale photovoltaics deployment","volume":"43","author":"Wadia","year":"2009","journal-title":"Environ. Sci. Technol."},{"key":"ref_58","unstructured":"NREL (2023). U.S. Solar Photovoltaic System and Energy Storage Cost Benchmarks, with Minimum Sustainable Price Analysis: Q1 2023, National Renewable Energy Laboratory."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1016\/j.rser.2015.02.057","article-title":"Energy payback time (EPBT) and energy return on energy invested (EROI) of solar photovoltaic systems: A systematic review and meta-analysis","volume":"47","author":"Bhandari","year":"2015","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"2168","DOI":"10.1021\/es071763q","article-title":"Emissions from photovoltaic life cycles","volume":"42","author":"Fthenakis","year":"2008","journal-title":"Environ. Sci. Technol."},{"key":"ref_61","doi-asserted-by":"crossref","unstructured":"Frischknecht, R., Stolz, P., Krebs, L., de Wild-Scholten, M., Sinha, P.V., Fthenakis, V.M., Kim, H.C., Raugei, M., and Stucki, M. (2020). Methodology Guidelines on Life Cycle Assessment of Photovoltaic Electricity, IEA. [4th ed.]. IEA PVPS Task 12, Report T12-18:2020.","DOI":"10.2172\/2308832"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"13728","DOI":"10.1038\/ncomms13728","article-title":"Re-assessment of net energy production and greenhouse gas emissions avoidance after 40 years of photovoltaics development","volume":"7","author":"Louwen","year":"2016","journal-title":"Nat. Commun."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/14\/2989\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T04:16:17Z","timestamp":1784175377000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/14\/2989"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,10]]},"references-count":62,"journal-issue":{"issue":"14","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["ma19142989"],"URL":"https:\/\/doi.org\/10.3390\/ma19142989","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,10]]}}}