合肥工业大学周儒课题组Advanced Science：籽晶诱导生长策略提升近空间升华法硫化锑太阳能电池性能

【文章信息】

籽晶诱导生长策略提升近空间升华法硫化锑太阳能电池性能

第一作者：武文韬

通讯作者：周儒*

单位：合肥工业大学

01引言

在众多新型光伏材料体系中，硫化锑（Sb₂S₃）因其环境友好、组分简单、原料丰富、稳定性良好等优点而受到广泛关注。近空间升华法（close-spaced sublimation, CSS）是一种成熟的物理沉积方法，用于制造大面积光伏薄膜。然而，CSS制备的吸收层通常具有高密度晶界（GB），导致严重缺陷诱导的载流子非辐射复合，进而造成较大的开路电压（V_OC）损失。因此，制备大晶粒Sb₂S₃薄膜对于消除或减少晶界的不利影响，提高Sb₂S₃太阳能电池的性能具有重要意义。在此背景下，作者创新性地提出一种籽晶诱导生长策略，通过在缓冲层上预先沉积Sb₂S₃籽晶层，提供高密度成核位点，促进后续CSS沉积Sb₂S₃薄膜的晶粒生长。这种方法可以显著提高Sb₂S₃薄膜的晶粒尺寸，有效降低薄膜中的缺陷密度，从而提升太阳能电池的开路电压和整体光电转换效率。利用这种新策略，研究团队为CSS制备Sb₂S₃太阳能电池的性能提升提供有效的解决方案。

02 成果展示

近日，合肥工业大学周儒课题组在著名学术期刊Advanced Science上发表题为“Enhanced performance of close-spaced sublimation processed antimony sulfide solar cells via seed-mediated growth”的研究论文。该文章针对Sb₂S₃薄膜太阳能电池中开路电压损失较大的问题，通过薄膜晶粒尺寸调控实现器件开路电压的有效提升，获得了高效Sb₂S₃薄膜太阳能电池。这项工作中，作者开发了一种有效的籽晶诱导生长策略来改善 CSS 沉积Sb₂S₃薄膜的晶粒生长，从而获得了具有低晶界密度的高质量吸收层薄膜。晶界密度的降低有助于抑制吸收层晶界和界面处的非辐射载流子复合，从而减少开路电压损失并提升Sb₂S₃太阳能电池的器件效率。基于该方法制备的Sb₂S₃太阳能电池实现了4.78% 的光电转换效率，远高于传统的CSS制备的器件（4.05%）。特别是，Sb₂S₃太阳能电池获得了 0.755 V 的高开路电压，这是迄今为止报道的蒸发和升华法加工Sb₂S₃器件的最高值。

03 图文导读

要点一：籽晶层增加Sb₂S₃薄膜晶粒尺寸

通过化学浴沉积（CBD）的Sb₂S₃籽晶层在CdS缓冲层的顶部上表现出均匀、致密的薄膜形貌，呈现非晶特性。在此基础上，利用CSS法制备大晶粒尺寸Sb₂S₃薄膜。系统表征揭示：平均晶粒尺寸从“无籽晶”样品的324 ± 39 nm增加到“有籽晶”样品的882 ± 119 nm，增加了一倍以上。“无籽晶”样品和“有籽晶”样品的膜厚度分别为775 ± 20和909 ± 10 nm。这表明，超薄籽晶层对Sb₂S₃薄膜的形貌有显著影响，但对薄膜的生长速率影响并不明显。

Figure 1. Schematic illustration of the device fabrication processes for planar Sb₂S₃ solar cells.

Figure 2. (a) Top-view and (b) cross-sectional-view SEM images of Sb₂S₃seed layer. (c) XRD patterns, (d, f) Top-view and (e, g) cross-sectional-view SEM images of Sb₂S₃ films prepared without and with seed. (h, i) Statistics of grain sizes for the “w/o seed” (part d) and “with seed” (part f) film samples.

要点二：籽晶层改善吸收层薄膜质量

Sb₂S₃籽晶层为后续CSS沉积Sb₂S₃主体吸收层提供了高密度成核位点，在薄膜生长过程中起着重要的调节作用。综合AFM和XPS结果，籽晶层有助于降低Sb₂S₃薄膜表面粗糙度，减少薄膜生长期间缺陷的产生，从而进一步改善从吸收层到背电极的空穴提取。在晶界处，与“无籽晶”样品相比，“有籽晶”样品的电导率更均匀、电导率也更高。对于籽晶诱导的吸收层薄膜，更小的电流波动有利于局部光电流的产生和收集，从而有效地抑制载流子复合。

Figure 3. (a, b) C-AFM analysis and (c, d) corresponding height profile and current of Sb₂S₃films prepared without and with the seed layer. (e, f) High-resolution XPS spectra of Sb 3d, and S 2p core levels of Sb₂S₃ films prepared without and with the seed layer.

要点三：Sb₂S₃薄膜太阳能电池器件性能

作者进一步制备了具有FTO/CdS/Sb₂S₃/Au平面结构的太阳能电池，器件表现出良好的性能以及重复性。最佳“有籽晶”器件的V_OC为0.743 V，J_SC为14.12 mA cm⁻²，FF为45.62%，PCE为4.78%。“有籽晶”器件平均光电转换效率为4.71%，“无籽晶”器件平均为4.00%，器件效率整体提高了10.18%。并且，获得的0.755 V最佳开路电压是迄今为止报道的蒸发和升华法沉积Sb₂S₃太阳能电池的最高值。

Figure 4. (a) Schematic illustration of the superstrate planar Sb₂S₃ solar cell with the configuration of FTO/CdS/Sb₂S₃/Au. (b) J-V curves and (c) EQE spectra of Sb₂S₃ solar cells prepared without and with the seed layer. (d) Device stability of Sb₂S₃solar cells prepared with the seed layer. (e) Statistics of the performance parameters (i.e., PCE, V_OC, J_SC, and FF) of Sb₂S₃ solar cells prepared without and with the seed layer.

要点四：太阳能电池器件物理

作者进一步阐明了薄膜缺陷特性并建立缺陷与器件性能之间的关联。通过电容-电压（C-V）测试揭示“有籽晶”器件内建电势（V_bi）的提高增强了异质界面处的能带弯曲，有助于了V_OC提高。此外，“有籽晶”器件具有更宽的耗尽区，有利于载流子的产生和提取，从而增强器件性能。暗J-V测试表明，籽晶层的引入抑制了漏电流，有利于提高J_SC和FF。超快瞬态吸收光谱（TAS）表明：与“无籽晶”器件相比，“有籽晶”薄膜样品中的载流子寿命更长，说明体相与界面处的载流子复合得到有效抑制。

Figure 5. (a) C-V and corresponding Mott-Schottky (1/C²~V) plots of the “w/o seed” and “with seed” Sb₂S₃ solar cells measured in the dark, and (b) logarithmic representation of a C-V derived carrier density profiles. (c) Nyquist plots for the “w/o seed” and “with seed” devices measured in the dark (the inset shows the equivalent circuit used for fitting). (d, e) The dependence of V_OC and J_SC on the light intensity for the “w/o seed” and “with seed” devices. (f) Dark J-Vcurves of the “w/o seed” and “with seed” devices. Calculation of characteristic parameters in equivalent circuit of solar cells based on J-V curves measured under one-sun illumination: (g) shunt conductance G, (h) series resistance R_Sand ideality factor A, (i) reverse saturation current density J₀.

Figure 6. (a, b) Transient absorption (TA) spectra obtained at 1, 10, 100, 1000, and 5000 ps pump-probe delay for Sb₂S₃thin films prepared without and with the seed layer. The excitation source is a pulsed laser with the excitation wavelength of 400 nm and the repetition frequency of 1000 Hz. (c, d) 2D TA spectroscopy pseudo-color images of Sb₂S₃thin films. (e, f) Transient kinetic decays (scatter) and corresponding biexponential curve fittings (solid line) monitored at 554 nm of Sb₂S₃thin films. ΔA is defined as the change in the absorption of the sample before and after pumping.

【文章链接】

Wentao Wu, Bo Tang, Lei Wan, Xiaoli Mao, Haolin Wang,Guoqing Tong, Tao Chen, Ru Zhou*. Enhanced performance of close-spaced sublimation processed antimony sulfide solar cells via seed-mediated growth. Advanced Science, 2024, 11, 2409312.

http://doi.org/10.1002/advs.202409312

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