【作者】 刘辉；

【导师】 靳正国；

【作者基本信息】 天津大学 ， 材料学， 2012， 博士

【摘要】 CuInSe₂（CIS）材料以其优越的光电性能，做为光吸收层材料在薄膜太阳能电池领域有着重要的地位和广阔的发展前景。纳米晶墨水法是近年来迅速发展的一种低成本、非真空环境下沉积CIS薄膜的技术。本文首次选择多元醇做为反应热溶剂，采用热注入工艺，成功制备出单相、近单分散、符合化学计量比的CIS纳米粒子、纳米片晶、纳米粒子和纳米片晶的混晶形态。将CIS纳米晶超声分散在乙醇中，制备出稳定的胶体墨水，采用浸渍-提拉成膜工艺，制备出高质量的CIS薄膜。进一步在Ar气中退火热处理，制备出高结晶性、高致密度、强烈（112）晶面取向的黄铜矿CIS薄膜。将墨水薄膜做为吸收层材料组装了Mo/CIS/CdS/i–ZnO, n–ZnO/Ag, Al型试验光伏器，得到了一定的光电转换效率。实验结果表明，以乙二醇（EG）、二乙二醇（DEG）和三乙二醇（TEG）做为反应热溶剂，水合肼（N₂H₄·H₂O）为还原剂制备的CIS纳米粒子的分散性会随着多元醇碳链的增加得到明显改善，TEG为反应热溶剂时制备的黄铜矿CIS纳米粒子的分散性最好，粒子呈现近球多变形形状，平均粒径约为10.5nm，且符合1/1/2相的化学计量比。TEG体系下，提高反应温度能增加CIS纳米粒子的平均尺寸和尺寸分布的均匀性。实验表明此体系是一个快速爆发、一步生成三元CIS晶核，迅速生长的过程，反应在1min左右就基本结束，进一步延长反应时间对于晶粒的长大影响不大，后期的奥斯瓦尔德熟化能促使晶粒略有长大，且粒径分布更窄，接近单分散。TEG体系下，以乙二胺（En）为还原剂时，改变热注入工艺程序能制备出直径为100⁶00nm的表面粗糙的多晶闪锌矿CIS纳米片和200⁴00nm之间、径厚比约为10的表面光滑的单晶闪锌矿CIS纳米片，且该纳米片具有闪锌矿（111）晶面取向。通过对不同反应时间产物的XRD、EDS、TEM和HRTEM的研究表明，CIS纳米片晶是先生成二元的CuSe纳米片，随后发生相变转变为CIS纳米片晶的。PVP的存在能明显改善CIS纳米片晶的分散性，机理是通过PVP强极性的酰基官能团与CIS纳米晶表面配位，利用空间位阻作用达到稳定分散的目的。溶液中同时加入N₂H₄·H₂O和En时，产物为CIS纳米粒子和纳米片的混晶，粒子和片晶的相对含量可以通过调节N₂H₄·H₂O和En的相对比例进行控制，增加En的相对含量能增加片晶的比例。CIS纳米晶墨水的分散性对于最终的成膜质量影响较大，分散性好的纳米晶通过浸渍-提拉成膜后较为平整、致密且无多孔现象，在Ar气热处理后致密度和结晶性都有一定提高。CIS纳米混晶薄膜的（112）择优取向会随着片晶含量比例的增加而加大，（112）方向择优取向因子能从1.2增加至14.5。闪锌矿CIS片晶薄膜580°C退火后会发生相变转化为热力学更稳定的黄铜矿CIS薄膜，同时薄膜的致密性和晶粒大小都有着明显的增加，且（112）晶面方向择优取向因子高达270.9。将CIS纳米粒子和纳米片混晶构成的薄膜热处理后做吸收层，组装Mo/CIS/CdS/i–ZnO/n–ZnO/Ag，Al薄膜试验电池，AM1.5光照下开路电压V_OC为255mV，短路电流J_SC为2.1mA·cm^-2，填充因子FF为0.29，光电转换效率达到0.16%。以580oC热处理后的CIS片晶薄膜组装的电池AM1.5光照下开路电压和短路电流能达到了249mV和1.97mA·cm^-2，填充因子达到了0.36，光电转换效率为0.18%。更多还原

【Abstract】 CuInSe₂（CIS） chalcopyrite compound is an important photo-absorbingsemiconductor in the development field of thin film solar cells due to its uniquephotoelectric property. In recent years, there have been increasing efforts indeveloping low-cost, non-vacuum solution process to fabricate CIS-based thin filmsolar cells, in which nanocrystals colloidal ink technique has been proposed. In thisdissertation, single-phase, well-dispersed and stoichiometric CuInSe₂nanoparticles,nanoplates and the mixed nanocrystals with near-granular polyhedral shape and flakeshape were synthesized by novel and facile hot-injection synthesis using polylol assolvents. The synthesized CIS nanocrystals were used to prepare stable colloidal inkswith ethanol solvent, and high-quality CIS thin films were deposited on glasssubstrates by dip-coating method using its colloidal inks. Well crystallized, dense andhighly （112） oriented chalcopyrite CIS thin films were obtained after annealing in Aratmosphere. The CIS thin films were used as light-absorbing layers to assemblephotovoltaic test devices with configuration of Mo/CIS/CdS/i–ZnO, n–ZnO/Ag, Alelectrode and photoelectric performances were measured.The research results showed that the dispersity of CIS nanoparticles synthesized byN2H4H2O-assisted hot-solvent process could be improved by using relatively largemolecule polyol such as triethylene glycol （TEG） when compared with ethylene （EG）and diethylene glycol （DEG）. Well-dispersed chalcopyrite CIS nanoparticles with112phase stoichiometry could be synthesized through TEG solvent process. The averagesize of CIS nanoparticles with polygonal morphology were about10.5nm. Highsynthetic temperature led to large average size and narrow size distribution. Thereaction analysis showed that nucleation of ternary CIS compound was rapid and thenuclei directly grew into CIS nanoparticles with a very fast growth duration within1min. Extending reaction time obviously unchanged the average size of the CISnanocrystals but the Ostwald ripening could lead to slight size increase and narrowsize distribution.Well-dispersed, polycrystalline sphalerite CIS nanoplates with rough plate surfaceand diameter ranged from100to600nm and well-despersed, hexagonal orhexagonal-like, monocrystalline,（111） oritened sphalerite CIS nanoplates withdiameter ranged from200to400nm and diameter-thickness-ratio of about10couldbe synthesized by using TEG as solvent and ethylenediamine （En） as reducing agent under different injection style. The products at different reaction stages wereinvestigated by XRD, TEM, HRTEM, SAED, XPS and EDX analysis. The resultsshowed binary CuSe nanoplates were firstly formed and then transformed to ternaryCIS nanoplates by gradual reduction of cupric Cu²⁺ to cuprous Cu⁺, In³⁺ and activeSe^2-participation at growing lattice sites. The PVP molecule can obviously improvethe dispersity of CIS nanocrystals by coordinating acly group on the surface ofnanocrystals. Well-dispersed sphalerite CIS nanocrystals with granular-andflaky-shaped mixed morphology were synthesized by both adding N₂H₄·H₂O and Enin TEG solvent. The relative ratio of granular-shaped CIS nanocrystals andflaky-shaped CIS nanocrystals could be tuned by the relative adding proportion ofN₂H₄·H₂O and En.The flat, dense and crack-free CIS thin films were prepared by dip-coating processusing well-dispersed CIS nanocrystals inks. Annealed in Ar atmosphere, the densityand crystallinity of the CIS thin films were enhanced. The （112） oriented factor of CISthin films rose from1.2to4.5by using the nanocrystals inks with nanoparticles andnanoplates mixed morphology. The sphalerite CIS phase would transformed to thechalcopyrite CIS phase which was more stable in thermodynamics after annealing at580°C in Ar atmosphere. The density and crystalline size of CIS thin films wereobviously enhanced and the （112） oriented factor reached270.9by using thenanocrystals inks with single nanoplates morphology after annealing at580°C.The CIS colloidal inks were used to deposit light-absorbing layers forphotovoltaic test devices with cell structure of Mo/CIS/CdS/i–ZnO, n–ZnO/Ag, Alelectrode. The V_OC, J_SC, FF and conversion efficience of the PV devices derived fromgranular-and flaky-shaped mixed nanocrystals inks were255mV,2.1mA·cm^-2,0.29and0.16%, respectively, under AM1.5irradiation. The V_OC, J_SC, FF and conversionefficience of PV cells from single CIS nanoplates inks were249mV,1.97mA·cm^-2，0.36and0.177%, respectively.更多还原