Cu2ZnSnSe4(CZTSe)鋅黃錫礦太陽能電池的晶體結構與Cu2InSe3相似，然而CZTSe中有著與Cu2InSe3截然不同的電性表現(例如在低溫時過低的短路電流以及填充因子)。此特殊電性表現的背後原因被認為是打開進一步改善其太陽能電池性能大門的鑰匙。因此，本論文致力於鋅黃錫礦太陽能電池缺陷系統的分析與控制。我們指出這些特殊的電性表現與其缺陷系統密切相關，並且我們也在CZTSSe太陽能電池中發現了深層的n型缺陷。由此可知，控制CZTSSe太陽能電池的缺陷系統對於進一步提升其電池效率是非常重要的。其中大量存在於CZTSSe太陽能銅鋅錯位缺陷被認為是低開路電壓的可能原因。為了控制CZTSSe太陽能電池的缺陷的系統，我們研發一個新的化合物 – (Ag,Cu)2ZnSnSe4以抑制銅鋅錯位缺陷的生成。我們證明了銅鋅錯為缺陷確實可藉由銀加入而抑制，我們也發現表面鈍化對於銀化合鋅黃錫礦太陽能電池的重要性。以有效的抑制銅鋅錯位缺陷輔以適當的表面鈍化，鋅黃錫礦太陽能電池性能可進一步改善。此外，銀取代銅也可以控制價帶位置，這使我們於未來研究能帶工程時能夠設計出更好的吸收層帶結構。這些研究結果為鋅黃錫礦太陽能電池的發展提供了新的途徑，並有望突破長年來鋅黃錫礦太陽能電池的發展瓶頸。

This thesis aims to gain more understanding of the defect system and the special electrical features of CZTSSe solar cells, which are believed to be the breadcrumbs to make the trustworthy strategy to improve the cell performance of kesterite solar cells. We point out that the special features (collapse of JSC and FF at low temperature) of CZTSSe solar cells are closely related to the defect system and we also find the possible existence of deep n-type defect in CZTSSe solar cells. To control the defect system of kesterite CZTSSe solar cells, we investigate a new compound – (Ag,Cu)2ZnSnSe4 to suppress the formation of CuZn antisite defects, which exist in kesterite CZTSSe in a large amount and are believed to be the reason for low VOC. We prove that the CuZn antisite defects are indeed suppressed by Ag substitution and find the importance of surface passivation in Ag-alloyed kesterite solar cells. With the effective suppression of CuZn and adequate surface passivation, the cell performance can be further improved. Moreover, the Ag substitution can also control the valence band maximum, which enables us to design a better band structure for the absorber layer. This study paves a new avenue for the development of kesterite solar cells and is promising for breaking the bottleneck of kesterite solar cells in the near future.

[1] “Global demand forecast,” EnergyTrend. [Online]. Available: http://pv.energytrend.com.tw/research/20131216-7428.html.
[2] M. J. Shiao, “First Solar Hits Record 22.1% Conversion Efficiency for CdTe Solar Cell,” Greentech Media. [Online]. Available: http://www.greentechmedia.com/articles/read/First-Solar-Hits-Record-22.1-Conversion-Efficiency-For-CdTe-Solar-Cell.
[3] A. Colthorpe, “Solar Frontier’s record efficiency 22.3% CIS cell faces ‘global market challenge,’” PV-Tech. [Online]. Available: http://www.pv-tech.org/news/solar-frontiers-record-efficiency-22.3-cis-cell-faces-global-market-challen.
[4] M. Osborne, “ZSW achieves world record CIGS lab cell efficiency of 22.6%,” PV-Tech. [Online]. Available: http://www.pv-tech.org/news/zsw-achieves-world-record-cigs-lab-cell-efficiency-of-22.6. [Accessed: 21-Jun-2016].
[5] “Best-Research-Cell Efficiencies,” NREL. [Online]. Available: http://www.nrel.gov/ncpv/images/efficiency_chart.jpg. [Accessed: 23-Jul-2016].
[6] S. R. Hall, T. J. Szymanski, and J. M. Stewart, “Kesterite Cu2(Zn,Fe)SnS4 and stannite Cu2(Fe,Zn)SnS4 structurally similar but distinct minerals,” Can. Mineral., vol. 16, no. 57, pp. 131–137, 1978.
[7] H. Matsushita, T. Maeda, A. Katsui, and T. Takizawa, “Thermal analysis and synthesis from the melts of Cu-based quaternary compounds Cu–III–IV–VI4 and Cu2–II–IV–VI4 (II=Zn,Cd; III=Ga,In; IV=Ge,Sn; VI=Se),” J. Cryst. Growth, vol. 208, no. 1–4, pp. 416–422, 2000.
[8] W. Schäfer and R. Nitsche, “Tetrahedral quaternary chalcogenides of the type Cu2 II IVS4(Se4),” Mater. Res. Bull., vol. 9, no. 5, pp. 645–654, 1974.
[9] C. Candelise, M. Winskel, and R. Gross, “Implications for CdTe and CIGS technologies production costs of indium and tellurium scarcity,” Prog. Photovolt. Res. Appl., vol. 20, no. 2012, pp. 816–831, 2014.
[10] H. Wang, “Progress in Thin Film Solar Cells Based on Cu2ZnSnS4,” Int. J. Photoenergy, vol. 2011, pp. 1–10, 2011.
[11] W. Wang, M. T. Winkler, O. Gunawan, T. Gokmen, T. K. Todorov, Y. Zhu, and D. B. Mitzi, “Device Characteristics of CZTSSe Thin‐Film Solar Cells with 12.6% Efficiency,” Adv. Energy Mater., vol. 4, no. 7, p. 1301465, 2014.
[12] TheNoise, “Pn-junction-equilibrium,” English Wikipedia. [Online]. Available: https://commons.wikimedia.org/wiki/File:Pn-junction-equilibrium.png. [Accessed: 04-Jul-2016].
[13] M. Britt, “Pn junction equilibrium,” English Wikipedia. [Online]. Available: https://commons.wikimedia.org/wiki/File:Pn_junction_equilibrium.svg. [Accessed: 04-Jul-2016].
[14] S. M. Sze and K. K. Ng, Physics of Semiconductor Devices. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2006.
[15] F. H. Pianezzi, “Electronic transport and doping mechanisms in Cu ( In , Ga ) Se 2 thin film solar cells,” ETH Zürich, 2014.
[16] V. Nadenau, U. Rau, A. Jasenek, and H. W. Schock, “Electronic properties of CuGaSe2-based heterojunction solar cells. Part I. Transport analysis,” J. Appl. Phys., vol. 87, no. 1, p. 584, 2000.
[17] C. H. L. Goodman, “The prediction of semiconducting properties in inorganic compounds,” J. Phys. Chem. Solids, vol. 6, no. 4, pp. 305–314, 1958.
[18] B. Pamplin, “A systematic method of deriving new semiconducting compounds by structural analogy,” J. Phys. Chem. Solids, vol. 25, no. 7, pp. 675–684, 1964.
[19] J. E. Jaffe and A. Zunger, “Theory of the band-gap anomaly in ABC2 chalcopyrite semiconductors,” Phys. Rev. B, vol. 29, no. 4, pp. 1882–1906, 1984.
[20] J. E. Jaffe and A. Zunger, “Electronic structure of the ternary chalcopyrite semiconductors CuAlS2, CuGaS2, CuInS2, CuAlSe2, CuGaSe2, and CuInSe2,” Phys. Rev. B, vol. 28, no. 10, pp. 5822–5847, 1983.
[21] S.-H. Wei and A. Zunger, “Band offsets and optical bowings of chalcopyrites and Zn-based II-VI alloys,” J. Appl. Phys., vol. 78, no. 6, p. 3846, 1995.
[22] S. Chen, X. G. Gong, and S. H. Wei, “Band-structure anomalies of the chalcopyrite semiconductors CuGaX2 versus AgGaX2(X=S and Se) and their alloys,” Phys. Rev. B - Condens. Matter Mater. Phys., vol. 75, no. 20, pp. 1–9, 2007.
[23] A. Walsh and S.-H. Wei, “Theoretical study of stability and electronic structure of Li(Mg,Zn)N alloys: A candidate for solid state lighting,” Phys. Rev. B, vol. 76, no. 19, p. 195208, 2007.
[24] Y. Z. Zhu, G. D. Chen, H. Ye, A. Walsh, C. Y. Moon, and S.-H. Wei, “Electronic structure and phase stability of MgO, ZnO, CdO, and related ternary alloys,” Phys. Rev. B, vol. 77, no. 24, p. 245209, 2008.
[25] D. J. Chadi, “Doping in ZnSe, ZnTe, MgSe, and MgTe wide-band-gap semiconductors,” Phys. Rev. Lett., vol. 72, no. 4, pp. 534–537, 1994.
[26] M. V. Yakushev, A. V. Mudryi, V. F. Gremenok, V. B. Zalesski, P. I. Romanov, Y. V. Feofanov, R. W. Martin, and R. D. Tomlinson, “Optical properties and band gap energy of CuInSe2 thin films prepared by two-stage selenization process,” J. Phys. Chem. Solids, vol. 64, no. 9–10, pp. 2005–2009, 2003.
[27] S. II Jung, K. H. Yoon, S. Ahn, J. Gwak, and J. H. Yun, “Fabrication and characterization of wide band-gap CuGaSe2 thin films for tandem structure,” Curr. Appl. Phys., vol. 10, no. 3, pp. S395–S398, 2010.
[28] A. Walsh, S. Chen, S. H. Wei, and X. G. Gong, “Kesterite thin-film solar cells: Advances in materials modelling of Cu2ZnSnS4,” Adv. Energy Mater., vol. 2, no. 4, pp. 400–409, 2012.
[29] S. Chen, X. G. Gong, A. Walsh, and S. H. Wei, “Crystal and electronic band structure of Cu2ZnSnX4 (X=S and Se) photovoltaic absorbers: First-principles insights,” Appl. Phys. Lett., vol. 94, no. 4, p. 41903, 2009.
[30] I. D. Olekseyuk, I. V. Dudchak, and L. V. Piskach, “Phase equilibria in the Cu2S–ZnS–SnS2 system,” J. Alloys Compd., vol. 368, no. 1–2, pp. 135–143, 2004.
[31] I. V. Dudchak and L. V. Piskach, “Phase equilibria in the Cu2SnSe3–SnSe2–ZnSe system,” J. Alloys Compd., vol. 351, no. 1–2, pp. 145–150, 2003.
[32] A. Nagoya, R. Asahi, R. Wahl, and G. Kresse, “Defect formation and phase stability of Cu2ZnSnS4 photovoltaic material,” Phys. Rev. B - Condens. Matter Mater. Phys., vol. 81, no. 11, p. 113202, 2010.
[33] S. Chen, X. G. Gong, A. Walsh, and S. H. Wei, “Defect physics of the kesterite thin-film solar cell absorber Cu2ZnSnS4,” Appl. Phys. Lett., vol. 96, no. 2, p. 21902, 2010.
[34] T. Maeda, S. Nakamura, and T. Wada, “First-principles calculations of vacancy formation in In-free photovoltaic semiconductor Cu2ZnSnSe4,” Thin Solid Films, vol. 519, no. 21, pp. 7513–7516, 2011.
[35] T. Godecke, T. Haalboom, and F. Ernst, “Phase equilibria of Cu-In-Se I. Stable states and nonequilibrium states of the In2Se3-Cu2Se subsystem,” ZEITSCHRIFT FUR Met., vol. 91, no. 8, pp. 622–634, 2000.
[36] F. Hergert and R. Hock, “Predicted formation reactions for the solid-state syntheses of the semiconductor materials Cu2SnX3 and Cu2ZnSnX4 (X = S, Se) starting from binary chalcogenides,” Thin Solid Films, vol. 515, no. 15, pp. 5953–5956, 2007.
[37] F. Hergert, S. Jost, R. Hock, M. Purwins, and J. Palm, “Predicted reaction paths for the formation of multinary chalcopyrite compounds,” Phys. status solidi, vol. 203, no. 11, pp. 2615–2623, 2006.
[38] R. Schurr, A. Hölzing, S. Jost, R. Hock, T. Voβ, J. Schulze, A. Kirbs, A. Ennaoui, M. Lux-Steiner, A. Weber, I. Kötschau, and H.-W. Schock, “The crystallisation of Cu2ZnSnS4 thin film solar cell absorbers from co-electroplated Cu-Zn-Sn precursors,” Thin Solid Films, vol. 517, no. 7, pp. 2465–2468, 2009.
[39] I. Repins, C. Beall, N. Vora, C. DeHart, D. Kuciauskas, P. Dippo, B. To, J. Mann, W.-C. Hsu, A. Goodrich, and R. Noufi, “Co-evaporated Cu2ZnSnSe4 films and devices,” Sol. Energy Mater. Sol. Cells, vol. 101, pp. 154–159, 2012.
[40] Y. S. Lee, T. Gershon, O. Gunawan, T. K. Todorov, T. Gokmen, Y. Virgus, and S. Guha, “Cu2ZnSnSe4 Thin-Film Solar Cells by Thermal Co-evaporation with 11.6% Efficiency and Improved Minority Carrier Diffusion Length,” Adv. Energy Mater., vol. 5, no. 7, p. 1401372, 2015.
[41] S. W. Shin, S. M. Pawar, C. Y. Park, J. H. Yun, J.-H. Moon, J. H. Kim, and J. Y. Lee, “Studies on Cu2ZnSnS4 (CZTS) absorber layer using different stacking orders in precursor thin films,” Sol. Energy Mater. Sol. Cells, vol. 95, no. 12, pp. 3202–3206, 2011.
[42] J. Li, Y. Zhang, H. Wang, L. Wu, J. Wang, W. Liu, Z. Zhou, Q. He, and Y. Sun, “On the growth process of Cu2ZnSn(S,Se)4 absorber layer formed by selenizing Cu-ZnS-SnS precursors and its photovoltaic performance,” Sol. Energy Mater. Sol. Cells, vol. 132, pp. 363–371, 2015.
[43] G. Brammertz, M. Buffière, S. Oueslati, H. ElAnzeery, K. Ben Messaoud, S. Sahayaraj, C. Köble, M. Meuris, and J. Poortmans, “Characterization of defects in 9.7% efficient Cu2ZnSnSe4-CdS-ZnO solar cells,” Appl. Phys. Lett., vol. 103, no. 16, p. 163904, 2013.
[44] T. K. Todorov, K. B. Reuter, and D. B. Mitzi, “High-Efficiency Solar Cell with Earth-Abundant Liquid-Processed Absorber,” Adv. Mater., vol. 22, no. 20, pp. E156–E159, 2010.
[45] H. Zhou, H.-S. Duan, W. Yang, Q. Chen, C.-J. Hsu, W.-C. Hsu, C.-C. Chen, and Y. Yang, “Facile single-component precursor for Cu2ZnSnS4 with enhanced phase and composition controllability,” Energy Environ. Sci., vol. 7, no. 3, pp. 998–1005, 2014.
[46] C.-J. Hsu, H.-S. Duan, W. Yang, H. Zhou, and Y. Yang, “Benign Solutions and Innovative Sequential Annealing Processes for High Performance Cu2ZnSn(Se,S)4 Photovoltaics,” Adv. Energy Mater., vol. 4, no. 6, p. 1301287, 2014.
[47] J. Zhong, Z. Xia, C. Zhang, B. Li, X. Liu, Y. Cheng, and J. Tang, “One-Pot Synthesis of Self-Stabilized Aqueous Nanoinks for Cu2ZnSn(S,Se)4 Solar Cells,” Chem. Mater., vol. 26, no. 11, pp. 3573–3578, 2014.
[48] X. Zeng, K. F. Tai, T. Zhang, C. W. J. Ho, X. Chen, A. Huan, T. C. Sum, and L. H. Wong, “Cu2ZnSn(S,Se)4 kesterite solar cell with 5.1% efficiency using spray pyrolysis of aqueous precursor solution followed by selenization,” Sol. Energy Mater. Sol. Cells, vol. 124, pp. 55–60, 2014.
[49] G. Larramona, S. Levcenko, S. Bourdais, A. Jacob, C. Choné, B. Delatouche, C. Moisan, J. Just, T. Unold, and G. Dennler, “Fine-Tuning the Sn Content in CZTSSe Thin Films to Achieve 10.8% Solar Cell Efficiency from Spray-Deposited Water-Ethanol-Based Colloidal Inks,” Adv. Energy Mater., vol. 5, no. 24, p. 1501404, 2015.
[50] G. Larramona, S. Bourdais, A. Jacob, C. Choné, T. Muto, Y. Cuccaro, B. Delatouche, C. Moisan, D. Péré, and G. Dennler, “Efficient Cu2ZnSnS4 solar cells spray coated from a hydro-alcoholic colloid synthesized by instantaneous reaction,” RSC Adv., vol. 4, no. 28, p. 14655, 2014.
[51] M. A. Hossain, Z. Tianliang, L. K. Keat, L. Xianglin, R. R. Prabhakar, S. K. Batabyal, S. G. Mhaisalkar, and L. H. Wong, “Synthesis of Cu(In,Ga)(S,Se)2 thin films using an aqueous spray-pyrolysis approach, and their solar cell efficiency of 10.5%,” J. Mater. Chem. A, vol. 3, no. 8, pp. 4147–4154, 2015.
[52] S. Chen, A. Walsh, X.-G. Gong, and S.-H. Wei, “Classification of Lattice Defects in the Kesterite Cu2ZnSnS4 and Cu2ZnSnSe4 Earth-Abundant Solar Cell Absorbers,” Adv. Mater., vol. 25, no. 11, pp. 1522–1539, 2013.
[53] S. Siebentritt and S. Schorr, “Kesterites-a challenging material for solar cells,” Prog. Photovolt. Res. Appl., vol. 20, no. 5, pp. 512–519, 2012.
[54] S. Das, K. C. Mandal, and R. N. Bhattacharya, Semiconductor Materials for Solar Photovoltaic Cells, vol. 218. Cham: Springer International Publishing, 2016.
[55] S. Chen, J. H. Yang, X. G. Gong, A. Walsh, and S. H. Wei, “Intrinsic point defects and complexes in the quaternary kesterite semiconductor Cu2ZnSnS4,” Phys. Rev. B - Condens. Matter Mater. Phys., vol. 81, no. 24, p. 245204, 2010.
[56] S. Schorr, “The crystal structure of kesterite type compounds: A neutron and X-ray diffraction study,” Sol. Energy Mater. Sol. Cells, vol. 95, no. 6, pp. 1482–1488, 2011.
[57] A. Lafond, L. Choubrac, C. Guillot-Deudon, P. Fertey, M. Evain, and S. Jobic, “X-ray resonant single-crystal diffraction technique, a powerful tool to investigate the kesterite structure of the photovoltaic Cu2ZnSnS4 compound.,” Acta Crystallogr. B. Struct. Sci. Cryst. Eng. Mater., vol. 70, no. Pt 2, pp. 390–4, 2014.
[58] T. Gokmen, O. Gunawan, T. K. Todorov, and D. B. Mitzi, “Band tailing and efficiency limitation in kesterite solar cells,” Appl. Phys. Lett., vol. 103, no. 10, p. 103506, 2013.
[59] Z. Yuan, S. Chen, H. Xiang, X. Gong, A. Walsh, J. Park, I. Repins, and S.-H. Wei, “Engineering Solar Cell Absorbers by Exploring the Band Alignment and Defect Disparity: The Case of Cu- and Ag-Based Kesterite Compounds,” Adv. Funct. Mater., vol. 25, no. 43, pp. 6733–6743, 2015.
[60] A. Carlson, “Auger Process,” Own work. [Online]. Available: https://commons.wikimedia.org/wiki/File:Auger_Process.svg. [Accessed: 28-Jul-2016].
[61] Wikipedia, “X-ray photoelectron spectroscopy,” Wikipedia. [Online]. Available: https://en.wikipedia.org/wiki/X-ray_photoelectron_spectroscopy. [Accessed: 29-Jul-2016].
[62] H. Tada and Q. Jin, “First-Transition Metal Oxocomplex–Surface-Modified Titanium(IV) Oxide for Solar Environmental Purification,” in Advanced Catalytic Materials - Photocatalysis and Other Current Trends, InTech, 2016.
[63] T. Walter, R. Herberholz, C. Müller, and H. W. Schock, “Determination of defect distributions from admittance measurements and application to Cu(In,Ga)Se2 based heterojunctions,” J. Appl. Phys., vol. 80, no. 8, p. 4411, 1996.
[64] U. Rau and H. W. Schock, “Electronic properties of Cu(In,Ga)Se2 heterojunction solar cells-recent achievements, current understanding, and future challenges,” Appl. Phys. A Mater. Sci. Process., vol. 69, no. 2, pp. 131–147, 1999.
[65] H. Katagiri, K. Jimbo, W. S. Maw, K. Oishi, M. Yamazaki, H. Araki, and A. Takeuchi, “Development of CZTS-based thin film solar cells,” Thin Solid Films, vol. 517, no. 7, pp. 2455–2460, 2009.
[66] Y. Cao, M. S. Denny, J. V Caspar, W. E. Farneth, Q. Guo, A. S. Ionkin, L. K. Johnson, M. Lu, I. Malajovich, D. Radu, H. D. Rosenfeld, K. R. Choudhury, and W. Wu, “High-Efficiency Solution-Processed Cu2ZnSn(S,Se)4 Thin-Film Solar Cells Prepared from Binary and Ternary Nanoparticles,” J. Am. Chem. Soc., vol. 134, no. 38, pp. 15644–15647, 2012.
[67] Q. Guo, G. M. Ford, W.-C. Yang, B. C. Walker, E. a Stach, H. W. Hillhouse, and R. Agrawal, “Fabrication of 7.2% efficient CZTSSe solar cells using CZTS nanocrystals.,” J. Am. Chem. Soc., vol. 132, no. 49, pp. 17384–6, 2010.
[68] D. A. R. Barkhouse, O. Gunawan, T. Gokmen, T. K. Todorov, and D. B. Mitzi, “Device characteristics of a 10.1% hydrazine-processed Cu2ZnSn(Se,S)4 solar cell,” Prog. Photovolt. Res. Appl., vol. 20, no. 1, pp. 6–11, 2012.
[69] S. G. Haass, M. Diethelm, M. Werner, B. Bissig, Y. E. Romanyuk, and A. N. Tiwari, “11.2% Efficient Solution Processed Kesterite Solar Cell with a Low Voltage Deficit,” Adv. Energy Mater., vol. 5, no. 18, p. 1500712, 2015.
[70] D. B. Mitzi, M. Yuan, W. Liu, A. J. Kellock, S. J. Chey, V. Deline, and A. G. Schrott, “A High-Efficiency Solution-Deposited Thin-Film Photovoltaic Device,” Adv. Mater., vol. 20, no. 19, pp. 3657–3662, 2008.
[71] O. Gunawan, T. Gokmen, C. W. Warren, J. D. Cohen, T. K. Todorov, D. A. R. Barkhouse, S. Bag, J. Tang, B. Shin, and D. B. Mitzi, “Electronic properties of the Cu2ZnSn(Se,S)4 absorber layer in solar cells as revealed by admittance spectroscopy and related methods,” Appl. Phys. Lett., vol. 100, no. 25, p. 253905, 2012.
[72] H.-S. Duan, W. Yang, B. Bob, C.-J. Hsu, B. Lei, and Y. Yang, “The Role of Sulfur in Solution-Processed Cu2ZnSn(S,Se)4 and its Effect on Defect Properties,” Adv. Funct. Mater., vol. 23, no. 11, pp. 1466–1471, 2013.
[73] C.-H. Hsu, Y.-S. Su, S.-Y. Wei, C.-H. Chen, W.-H. Ho, C. Chang, Y.-H. Wu, C.-J. Lin, and C.-H. Lai, “Na-induced efficiency boost for Se-deficient Cu(In,Ga)Se2 solar cells,” Prog. Photovolt. Res. Appl., vol. 23, no. 11, pp. 1621–1629, 2015.
[74] J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High Efficiency Cu2ZnSn(S,Se)4 Solar Cells by Applying a Double In2S3/CdS Emitter,” Adv. Mater., vol. 26, no. 44, pp. 7427–7431, 2014.
[75] D. B. Mitzi, O. Gunawan, T. K. Todorov, K. Wang, and S. Guha, “The path towards a high-performance solution-processed kesterite solar cell,” Sol. Energy Mater. Sol. Cells, vol. 95, no. 6, pp. 1421–1436, 2011.
[76] J. Jiang, G. Oberdörster, and P. Biswas, “Characterization of size, surface charge, and agglomeration state of nanoparticle dispersions for toxicological studies,” J. Nanoparticle Res., vol. 11, no. 1, pp. 77–89, 2009.
[77] M. Burgelman, P. Nollet, and S. Degrave, “Modelling polycrystalline semiconductor solar cells,” Thin Solid Films, vol. 361–362, pp. 527–532, 2000.
[78] C. H. Cai, S. Y. Wei, W. C. Huang, J. Lin, T. H. Yeh, and C. H. Lai, “Efficiency enhancement by adding SnS powder during selenization for Cu2ZnSn(S,Se)4 thin film solar cells,” Sol. Energy Mater. Sol. Cells, vol. 145, pp. 296–302, 2016.
[79] A. Redinger, D. M. Berg, P. J. Dale, and S. Siebentritt, “The Consequences of Kesterite Equilibria for Efficient Solar Cells,” J. Am. Chem. Soc., vol. 133, no. 10, pp. 3320–3323, 2011.
[80] Y.-C. Liao, F.-Y. Yang, and C. Ting, “INK COMPOSITION,” US 8,771,555 B2, 2014.
[81] J. Lyklema, Fundamentals of Interfaceand Colloid Science : Solid–Liquid Interfaces. New York: Academic Press, 1995.
[82] A. V. Delgado, F. González-Caballero, R. J. Hunter, L. K. Koopal, and J. Lyklema, “Measurement and Interpretation of Electrokinetic Phenomena (IUPAC Technical Report),” Pure Appl. Chem., vol. 77, no. 10, pp. 1753–1805, 2005.
[83] V. L. Boris and A. V Novichikhin, “Mechanism of thermal decomposition of hydrated copper nitrate in vacuo,” Spectrochim. Acta Part B, vol. 50, pp. 1459–1468, 1995.
[84] M. Maneva and N. Petrov, “On the thermal decomposition of Zn(NO3)2·6H2O and its deuterated analogue,” J. Therm. Anal., vol. 35, no. 7, pp. 2297–2303, 1989.
[85] D. Li, J. Wang, X. Li, and H. Liu, “Effect of ultrasonic frequency on the structure and sonophotocatalytic property of CdS/TiO2 nanocomposite,” Mater. Sci. Semicond. Process., vol. 15, no. 2, pp. 152–158, 2012.
[86] W. Yang, H.-S. Duan, B. Bob, H. Zhou, B. Lei, C.-H. Chung, S.-H. Li, W. W. Hou, and Y. Yang, “Novel solution processing of high-efficiency Earth-abundant Cu2 ZnSn(S,Se)4 solar cells.,” Adv. Mater., vol. 24, no. 47, pp. 6323–9, 2012.
[87] A. Redinger, K. Hönes, X. Fontané, V. Izquierdo-Roca, E. Saucedo, N. Valle, A. Pérez-Rodríguez, and S. Siebentritt, “Detection of a ZnSe secondary phase in coevaporated Cu2ZnSnSe4 thin films,” Appl. Phys. Lett., vol. 98, no. 10, p. 101907, 2011.
[88] Q. Guo, G. M. Ford, H. W. Hillhouse, and R. Agrawal, “Sulfide Nanocrystal Inks for Dense Cu(In1−xGax)(S1−ySey)2 Absorber Films and Their Photovoltaic Performance,” Nano Lett., vol. 9, no. 8, pp. 3060–3065, 2009.
[89] N. Moritake, Y. Fukui, M. Oonuki, K. Tanaka, and H. Uchiki, “Preparation of Cu2ZnSnS4 thin film solar cells under non-vacuum condition,” Phys. Status Solidi, vol. 6, no. 5, pp. 1233–1236, 2009.
[90] T. Todorov, M. Kita, J. Carda, and P. Escribano, “Cu2ZnSnS4 films deposited by a soft-chemistry method,” Thin Solid Films, vol. 517, no. 7, pp. 2541–2544, 2009.
[91] O. Gunawan, T. K. Todorov, and D. B. Mitzi, “Loss mechanisms in hydrazine-processed Cu2ZnSn(Se,S)4 solar cells,” Appl. Phys. Lett., vol. 97, no. 23, p. 233506, 2010.
[92] D. B. Mitzi, O. Gunawan, T. K. Todorov, and D. A. R. Barkhouse, “Prospects and performance limitations for Cu-Zn-Sn-S-Se photovoltaic technology,” Philos. Trans. R. Soc. A Math. Phys. Eng. Sci., vol. 371, no. 1996, pp. 20110432–20110432, 2013.
[93] C.-H. M. Chuang, A. Maurano, R. E. Brandt, G. W. Hwang, J. Jean, T. Buonassisi, V. Bulović, and M. G. Bawendi, “Open-Circuit Voltage Deficit, Radiative Sub-Bandgap States, and Prospects in Quantum Dot Solar Cells,” Nano Lett., vol. 15, no. 5, pp. 3286–3294, 2015.
[94] J. Lee, J. D. Cohen, and W. N. Shafarman, “The determination of carrier mobilities in CIGS photovoltaic devices using high-frequency admittance measurements,” Thin Solid Films, vol. 480–481, pp. 336–340, 2005.
[95] M. Burgelman and P. Nollet, “Admittance spectroscopy of thin film solar cells,” Solid State Ionics, vol. 176, no. 25–28, pp. 2171–2175, 2005.
[96] J. Li, Y. Zhang, W. Zhao, D. Nam, H. Cheong, L. Wu, Z. Zhou, and Y. Sun, “A Temporary Barrier Effect of the Alloy Layer During Selenization: Tailoring the Thickness of MoSe2 for Efficient Cu2ZnSnSe4 Solar Cells,” Adv. Energy Mater., vol. 5, no. 9, p. 1402178, 2015.
[97] R. Caballero, C. A. Kaufmann, T. Eisenbarth, A. Grimm, I. Lauermann, T. Unold, R. Klenk, and H. W. Schock, “Influence of Na on Cu(In,Ga)Se2 solar cells grown on polyimide substrates at low temperature: Impact on the Cu(In,Ga)Se2/Mo interface,” Appl. Phys. Lett., vol. 96, no. 9, p. 92104, 2010.
[98] R. Würz, D. Fuertes Marrón, A. Meeder, A. Rumberg, S. M. Babu, T. Schedel-Niedrig, U. Bloeck, P. Schubert-Bischoff, and M. C. Lux-Steiner, “Formation of an interfacial MoSe2 layer in CVD grown CuGaSe2 based thin film solar cells,” Thin Solid Films, vol. 431–432, pp. 398–402, 2003.
[99] X. Luo, M. M. Islam, M. A. Halim, C. Xu, T. Sakurai, N. Sakai, T. Kato, H. Sugimoto, H. Tampo, H. Shibata, S. Niki, and K. Akimoto, “Defect study of Cu2ZnSn(S,Se)4 thin film with different Cu/Sn ratio by admittance spectroscopy,” in 2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014, 2014, no. 1, pp. 2366–2369.
[100] M. Nichterwitz and T. Unold, “Numerical simulation of cross section electron-beam induced current in thin-film solar-cells for low and high injection conditions,” J. Appl. Phys., vol. 114, no. 13, p. 134504, 2013.
[101] T. Gokmen, O. Gunawan, and D. B. Mitzi, “Minority carrier diffusion length extraction in Cu2ZnSn(Se,S)4 solar cells,” J. Appl. Phys., vol. 114, no. 11, p. 114511, 2013.
[102] B. Shin, O. Gunawan, Y. Zhu, N. A. Bojarczuk, S. J. Chey, and S. Guha, “Thin film solar cell with 8.4% power conversion efficiency using an earth-abundant Cu2ZnSnS4 absorber,” Prog. Photovolt. Res. Appl., vol. 21, no. 1, pp. 72–76, 2013.
[103] T. Paul Weiss, A. Redinger, J. Luckas, M. Mousel, and S. Siebentritt, “Admittance spectroscopy in kesterite solar cells: Defect signal or circuit response,” Appl. Phys. Lett., vol. 102, no. 20, p. 202105, 2013.
[104] M. Danilson, E. Kask, N. Pokharel, M. Grossberg, M. Kauk-Kuusik, T. Varema, and J. Krustok, “Temperature dependent current transport properties in Cu2ZnSnS4 solar cells,” Thin Solid Films, vol. 582, pp. 162–165, 2015.
[105] S. Giraldo, M. Neuschitzer, T. Thersleff, S. López-Marino, Y. Sánchez, H. Xie, M. Colina, M. Placidi, P. Pistor, V. Izquierdo-Roca, K. Leifer, A. Pérez-Rodríguez, and E. Saucedo, “Large Efficiency Improvement in Cu2ZnSnSe4 Solar Cells by Introducing a Superficial Ge Nanolayer,” Adv. Energy Mater., vol. 5, no. 21, p. 1501070, 2015.
[106] Z. Su, J. M. R. Tan, X. Li, X. Zeng, S. K. Batabyal, and L. H. Wong, “Cation Substitution of Solution-Processed Cu2ZnSnS4 Thin Film Solar Cell with over 9% Efficiency,” Adv. Energy Mater., vol. 5, no. 19, p. 1500682, 2015.
[107] C. J. Hages, M. J. Koeper, and R. Agrawal, “Optoelectronic and material properties of nanocrystal-based CZTSe absorbers with Ag-alloying,” Sol. Energy Mater. Sol. Cells, vol. 145, pp. 342–348, 2016.
[108] M. Gloeckler and J. R. Sites, “Efficiency limitations for wide-band-gap chalcopyrite solar cells,” Thin Solid Films, vol. 480–481, pp. 241–245, 2005.
[109] S. Sharbati and J. R. Sites, “Impact of the band offset for n-Zn(O,S)/p-Cu(In,Ga)Se2 solar cells,” IEEE J. Photovoltaics, vol. 4, no. 2, pp. 697–702, 2014.
[110] Q. Guo, G. M. Ford, W. C. Yang, C. J. Hages, H. W. Hillhouse, and R. Agrawal, “Enhancing the performance of CZTSSe solar cells with Ge alloying,” Sol. Energy Mater. Sol. Cells, vol. 105, pp. 132–136, 2012.
[111] T. Maeda, S. Nakamura, and T. Wada, “FIRST-PRINCIPLES STUDY OF IN-FREE PHOTOVOLTAIC COMPOUNDS, I2-II-IVSe4 (I= Cu, Ag; II= Zn, Cd, Hg; IV= Si, Ge, Sn; VI= S, Se),” in 26th European Photovoltaic Solar Energy Conference and Exhibition, 2011, pp. 2836–2839.
[112] H. Cui, X. Liu, F. Liu, X. Hao, N. Song, and C. Yan, “Boosting Cu2ZnSnS4 solar cells efficiency by a thin Ag intermediate layer between absorber and back contact,” Appl. Phys. Lett., vol. 104, p. 41115, 2014.
[113] T. Tabata, T. Maeda, and T. Wada, “Preparation and properties of In-free photovoltaic material (Cu1-xAgx)2ZnSnSe4,” in EMRS Spring Meeting, 2011.
[114] W. Gong, T. Tabata, K. Takei, M. Morihama, T. Maeda, and T. Wada, “Crystallographic and optical properties of (Cu,Ag)2ZnSnS4 and (Cu,Ag)2ZnSnSe4 solid solutions,” Phys. status solidi, vol. 12, no. 6, pp. 700–703, 2015.
[115] L. Kuipers and R. E. Palmer, “Influence of island mobility on island size distributions in surface growth,” Phys. Rev. B, vol. 53, no. 12, pp. R7646–R7649, 1996.
[116] W.-C. Wen, R. V. Chepulskii, L.-W. Wang, S. Curtarolo, and C.-H. Lai, “Accelerating disorder–order transitions of FePt by preforming a metastable AgPt phase,” Acta Mater., vol. 60, no. 20, pp. 7258–7264, 2012.
[117] J. H. Boyle, B. E. McCandless, W. N. Shafarman, and R. W. Birkmire, “Structural and optical properties of (Ag,Cu)(In,Ga)Se2 polycrystalline thin film alloys,” J. Appl. Phys., vol. 115, no. 22, p. 223504, 2014.
[118] S. Nakamura, T. Maeda, T. Tabata, and T. Wada, “First-principles study of indium-free photovotaic compouns Ag2ZnSnSe4 and Cu2ZnSnSe4,” in Photovoltaic Specialists Conference (PVSC), 37th IEEE, 2011, pp. 2–5.
[119] M. Robbins, J. C. Phillips, and B. Laboratories, “Solid Solution Formation in the Systems CuMIIIX2-AgMIIIX2 WHERE MIII= AI, Ga, In AND X2=S, Se,” J. Phys. Chem. Solids, vol. 34, pp. 1205–1209, 1973.
[120] I. Tsuji, Y. Shimodaira, H. Kato, H. Kobayashi, and A. Kudo, “Novel stannite-type complex sulfide photocatalysts AI2-Zn-AIV-S4 (AI = Cu and Ag; A IV = Sn and Ge) for hydrogen evolution under visible-light irradiation,” Chem. Mater., vol. 22, no. 8, pp. 1402–1409, 2010.
[121] H. Neumann, “Optical properties and electronic band structure of CuInSe2,” Sol. Cells, vol. 16, pp. 317–333, 1986.
[122] J. E. Rowe and J. L. Shay, “Extension of the Quasicubic Model to Ternary Chalcopyrite Crystals,” Phys. Rev. B, vol. 3, no. 2, pp. 451–453, 1971.
[123] T. Gershon, Y. S. Lee, P. Antunez, R. Mankad, S. Singh, D. Bishop, O. Gunawan, M. Hopstaken, and R. Haight, “Photovoltaic Materials and Devices Based on the Alloyed Kesterite Absorber (AgxCu1-x)2ZnSnSe4,” Adv. Energy Mater., vol. 6, no. 10, p. 1502468, 2016.
[124] L. C. Kimerling, “Influence of deep traps on the measurement of free-carrier distributions in semiconductors by junction capacitance techniques,” J. Appl. Phys., vol. 45, no. 4, p. 1839, 1974.
[125] F. Pianezzi, P. Reinhard, A. Chirilă, B. Bissig, S. Nishiwaki, S. Buecheler, and A. N. Tiwari, “Unveiling the effects of post-deposition treatment with different alkaline elements on the electronic properties of CIGS thin film solar cells.,” Phys. Chem. Chem. Phys., vol. 16, no. 19, pp. 8843–51, 2014.
[126] C. P. Thompson, S. Hegedus, W. Shafarman, and D. Desai, “Temperature dependence of VOC in CdTe and Cu(InGa)(SeS)2-based solar cells,” in 2008 33rd IEEE Photovolatic Specialists Conference, 2008, no. T 88, pp. 1–6.
[127] S. S. Hegedus and W. N. Shafarman, “Thin-Film Solar Cells: Device Measurements and Analysis,” Prog. Photovolt. Res. Appl., vol. 12, no. 2–3, pp. 155–176, 2004.
[128] M. Turcu, O. Pakma, and U. Rau, “Interdependence of absorber composition and recombination mechanism in Cu(In,Ga)(Se,S)2 heterojunction solar cells,” Appl. Phys. Lett., vol. 80, no. 14, pp. 2598–2600, 2002.
[129] T. Gershon, B. Shin, N. Bojarczuk, M. Hopstaken, D. B. Mitzi, and S. Guha, “The role of sodium as a surfactant and suppressor of non-radiative recombination at internal surfaces in Cu2ZnSnS4,” Adv. Energy Mater., vol. 5, no. 2, pp. 1–8, 2015.
[130] Y.-R. Lin, V. Tunuguntla, S.-Y. Wei, W.-C. Chen, D. Wong, C.-H. Lai, L.-K. Liu, L.-C. Chen, and K.-H. Chen, “Bifacial sodium-incorporated treatments: Tailoring deep traps and enhancing carrier transport properties in Cu2ZnSnS4 solar cells,” Nano Energy, vol. 16, pp. 438–445, 2015.
[131] N. K. Elumalai and A. Uddin, “Open circuit voltage of organic solar cells: an in-depth review,” Energy Environ. Sci., vol. 5692, pp. 1–5, 2016.
[132] R. Caballero, C. A. Kaufmann, T. Eisenbarth, M. Cancela, R. Hesse, T. Unold, A. Eicke, R. Klenk, and H. W. Schock, “The influence of Na on low temperature growth of CIGS thin film solar cells on polyimide substrates,” Thin Solid Films, vol. 517, no. 7, pp. 2187–2190, 2009.