GaAs基高效多结太阳电池研究进展

随着半导体太阳电池制备工艺的发展,基于GaAs的Ⅲ-Ⅴ族化合物半导体电池光电转换效率不断提高,是目前世界上最具竞争力的新一代太阳电池,成为空间太阳电池领域的研究热点。文章详细评述了GaAs基系双结、三结及三结以上太阳电池的研究历程与最新技术发展现状,并对它的发展前景进行了展望。     

集成式垂直多结太阳电池的设计与实现

利用高速热迁移掺杂工艺制成垂直多结 PN结阵列 ,同时扩散短路区在阵列的一端连接所有的 P区 ,形成一个单元电池 ,对大片不分割单元电池 ,只加宽金属线条将相邻单元电池的正负极短路形成欧姆接触 ,这样的单元电池的连接就是集成电池。这样的器件有两个光照面 ,电极对光的遮蔽面积非常小。     

多结太阳电池辐射损伤的电致发光研究

建立了电致发光测试方法,对一种国产GaInP/GaAs/Ge三结太阳电池1MeV电子辐照后各子电池的辐照特性进行了研究,并与光谱响应结果进行了比较。讨论了GaInP/GaAs/Ge三结太阳电池的辐射损伤机理。     

多结太阳电池用P型锗单晶片去蜡技术研究

在多结太阳电池结构中,P型锗单晶片不仅作为衬底,也是整体电池结构中的一个结。在外延生长过程中,需要进行多次异质外延生长,因此,对P型锗单晶片的表面质量提出了更高的要求。通过对P型锗片去蜡技术的研究,提高了锗片表面质量,降低了外延生长过程中雾缺陷的比例。     

GaAs基Ⅲ-Ⅴ族多结太阳电池技术研究进展

GaAs太阳电池由于其性能优越,成为了光伏领域的发展重点。简单介绍了GaAs基Ⅲ-Ⅴ族多结太阳电池的应用和研究进展,并对其发展趋势进行了展望。     

渐变带隙Cd1-xZnxTe太阳电池光电转换效率的数值模拟

Cd1-xZnxTe是直接带隙半导体材料,其禁带宽度随x值的变化在1.45eV～2.26eV间连续可调.将具有渐变带隙结构的材料作为太阳电池的光吸收层,可以在近背表面的薄层内产生一个准电场.该电场不仅能将俄歇复合发生的位置有效局域化,而且还可降低由表面复合引起的载流子损耗,增强光生载流子的收集效率,进而提高电池的光电转换效率.用渐变带隙Cd1-xZnxTe多晶薄膜替代了传统CdTe薄膜太阳电池中的均匀相CdTe光吸收层,并用AMPS软件模拟分析了渐变带隙Cd1-xZnxTe太阳电池的光电响应特性.经计算,该电池在理想情况下(无界面态、有背面场,正背面反射率分别为0和1)的光电转换效率高达41%.     

GaAs太阳电池的体电阻及旁路漏电对电池结特性的影响

复合电流是液相外延GaAs太阳电池暗电流的主要成分。扫描电镜观察表明,旁路电流主要来源于太阳电池结区的杂质。串联电阻主要来源于电池p型GaAs层的薄层电阻及正面电极的体电阻。串联电阻降低了电池的短路电流,旁路电阻降低了电池的开路电压。减小电池p-GaAs层的薄层电阻是提高电池效率的重要途径。     

GaAs/Ge太阳电池异常I-V特性曲线分析

分析了GaAs/Ge单结太阳电池研制中两种异常I-V特性曲线出现的主要原因:GaAs/Ge界面的相互扩散,形成附加结或附加势垒;并获得与实验有很好吻合的计算模拟结果,进一步证实了理论分析.此外,在上述分析的指导下,通过降低生长温度和优化成核条件,成功获得了效率为20.95%(AM0,25℃,2cm× 4cm)的GaAs/Ge太阳电池.     

GaAs/Ge太阳电池异常I-V特性曲线分析

分析了GaAs/Ge单结太阳电池研制中两种异常I-V特性曲线出现的主要原因：GaAs/Ge界面的相互扩散，形成附加结或附加势垒；并获得与实验有很好吻合的计算模拟结果，进一步证实了理论分析. 此外，在上述分析的指导下，通过降低生长温度和优化成核条件，成功获得了效率为20.95% (AM0,25℃, 2cm×4cm）的GaAs/Ge太阳电池.     

选择性发射极参数对太阳电池光电特性的影响

选择性发射极太阳电池具有独特的器件结构及优异的光电特性。基于M·Tucci等人实际制作的一款选择性发射极太阳电池,利用TCAD软件MEDICI建立了其器件结构模型,在比实验更大的参数范围内分析了发射区厚度、n+区和n区掺杂浓度等物理量对太阳电池光电转换效率的影响。结果表明,发射区的最佳厚度约为0·6μm,该厚度下n+区的最佳掺杂浓度约为6×1020cm-3,增加n区浓度则会导致转换效率下降。在优化发射区方块电阻的基础上考虑少子寿命的优化,可获得高达19·16%的光电转换效率,接近当前较大面积同类太阳电池的最佳水平,为实际制备大面积高效单晶硅太阳电池提供了有益的参考。     

Performance Mapping of Multijunction Solar Cells Based on Electroluminescence

Electroluminescence intensity maps of all three subcells of space grade III–V multijunction cells were obtained with the help of dedicated imaging sensors at a range of different injection currents. Solely based on these data, making use of the homogeneity of one subcell, the local diode properties of an equivalent single junction cell were obtained and converted into spatial distributions of open circuit voltage $(V_{rm oc})$ and current at a fixed operating voltage $(I_{rm op})$. On a sample basis of more than 200 cells, $V_{rm oc}$ and $I_{rm op}$ characterizing the entire cell were determined with an accuracy of $pm$3 mV and $pm$5 mA, respectively.      

Gold(III) Corroles for High Performance Organic Solar Cells

While the use of molecular materials having long‐lived triplet excited state(s) for harvesting solar energy could be an effective approach to boost up the power conversion efficiency (PCE) of organic solar cells (OSCs), the performances of this kind of OSCs as reported in the literature are low (< 2.9% PCE attained for the vacuum‐deposited OSCs). Herein is described the realization of high performance OSCs by using gold(III) 5,10,15‐triphenylcorrole ( Au‐C1 ), gold(III) 10‐(p‐trifluoromethylphenyl)‐5,15‐diphenylcorrole ( Au‐C2 ), and gold(III) 10‐(pentafluorophenyl)‐5,15‐diphenyl‐corrole ( Au‐C3 ), as electron‐donors. These gold(III) corroles display excited state lifetimes of ≥ 25 μs and low emission quantum yields of < 0.15%. With the complexes Au‐C1 , Au‐C2 , and Au‐C3 , vacuum‐deposited OSCs, which give PCEs of 2.7%, 3.0%, and 1.8%, respectively, are fabricated. The PCE can be further boosted up to 4.0% after thermal treatment of the OSC devices. Meanwhile, a solution‐processed OSC based on Au‐C2 with a high PCE of 6.0% is fabricated. These PCE values are among the best reported for both types of vacuum‐deposited and solution‐processed OSCs fabricated with metal‐organic complexes having long‐lived excited states as electron‐donor material. The underlying mechanism for the inferior performance of the reported OSCs is discussed.     

Conformation Locking on Fused‐Ring Electron Acceptor for High‐Performance Nonfullerene Organic Solar Cells

In this work, sidechain engineering on conjugated fused‐ring acceptors for conformation locking is demonstrated as an effective molecular design strategy for high‐performance nonfullerene organic solar cells (OSCs). A novel nonfullerene acceptor (ITC6‐IC) is designed and developed by introducing long alkyl chains into the terminal electron‐donating building blocks. ITC6‐IC has achieved definite conformation with a planar structure and better solubility in common organic solvents. The weak electron‐donating hexyl upshifts the lowest unoccupied molecular orbital level of ITC6‐IC, resulting in a higher V_OC in comparison to the widely used ITIC. The OSCs based on PBDB‐T:ITC6‐IC reveal a promising power conversion efficiency of 11.61% and an expected high V_OC of 0.97 V. The weaker π–π stacking induced by steric hindrance affords ITC6‐IC with enhanced compatibility with polymer donors. The blend film treated with suitable thermal annealing exhibits a fibril crystallization feature with a good bicontinuous network morphology. The results indicate that the molecular design approach of ITC6‐IC can be inspirational for future development of nonfullerene acceptors for high efficiency OSCs.     

高效率有机太阳电池的理论建模

采用综合考虑温度、电场强度、载流子浓度的普遍迁移率模型,利用实际太阳能光谱和非富勒烯材料的吸收系数来计算载流子的产生,结合漂移扩散方程、电流连续性方程等对高效率有机太阳电池进行理论建模。利用该模型计算了器件的电流-电压曲线、开路电压-光照强度曲线和短路电流-光照强度曲线。结果发现,利用该模型计算的电流-电压曲线与实验数据符合很好,其他两种曲线也与实验数据符合较好。此外,利用该模型分析了能量无序度对器件性能的影响,结果表明减小材料的能量无序度可以提高有机太阳电池的性能。     

Crumple Durable Ultraflexible Organic Solar Cells with an Excellent Power-per-Weight Performance

Ultraflexible and ultra-lightweight organic solar cells (OSCs) have attracted great attention in terms of power supply in wearable electronic systems. Here, ultrathin and ultra-lightweight OSCs, with a total thickness of less than 3 µm, with excellent mechanical properties in terms of their flexibility and ability to be stretched are demonstrated. A stabilized power conversion efficiency (PCE) of 15.5% and unprecedented power-per-weight of 32.07 W g⁻¹ at a weight of 4.83 g m⁻² is achieved, which represents one of the best-performing OSCs based on ultrathin foils substrate reported to date. The ternary strategy introduces the third component of amorphous conformation of the PC₇₁BM molecule, which can slightly reduce crystallization and aggregates without decreasing the electron mobility, thereby reducing rigidity and brittleness of the active layer. The increase in the ductility of the active layer significantly improves the mechanical flexibility of the device, resulting in over 90% retention in the PCE after 200 stretching–compression cycles. In addition, the ternary device exhibits excellent stability when stored in a N₂-filled glove box, resulting in the PCE retaining over 95% of its initial efficiency even after 1000 h. This ultraflexible and ultra-lightweight photovoltaic foils constitute a major step toward the integration of power supply into malleable electronic textiles.     

a-Si:C:H and a-Si:N:H Thin Films Obtained by PECVD for Applications in Silicon Solar Cells

Hydrogenated amorphous silicon-carbon (a-Si:C:H) and hydrogenated silicon-nitrogen (a-Si:N:H) antireflective films were deposited by plasma-enhanced chemical vapor deposition (PECVD) at 13.56 MHz in SiH₄ + CH₄ and SiH₄ + NH₃ gaseous mixtures of various compositions. The silicon and glass samples were investigated by optical spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). A correlation between film properties and process parameters was found. The refractive index decreased and the energy gap increased with an increase of carbon and nitrogen in the films. For some process parameters, it was possible to obtain smooth, hydrogen rich, and homogeneous films of low reflectivity. The silicon solar cells with antireflective coatings revealed an increase in efficiency.     

Near‐Infrared Small Molecule Acceptor Enabled High‐Performance Nonfullerene Polymer Solar Cells with Over 13% Efficiency

One of the most promising approaches to achieve high‐performance polymer solar cells (PSCs) is to develop nonfullerene small molecule acceptors (SMAs) with an absorption extending to the near‐infrared (NIR) region. In this work, two novel SMAs, namely, BTTIC and BTOIC, are designed and synthesized, with optical bandgaps (E_g^opt) of 1.47 and 1.39 eV, respectively. Desipte the narrow E_g^opt, the PBDB‐T:BTTIC‐ and PBDB‐T:BTOIC‐based PSCs can maintain high V_OCs of over 0.90 and 0.86 V, respectively, with low energy losses (E_loss) < 0.6 eV. Meanwhile, due to the favorable morphology of the PBDB‐T:BTTIC blend, balanced carrier mobilities are achieved. The high external quantum efficiencies enable a high power conversion efficiency (PCE) up to 13.18% for the PBDB‐T:BTTIC‐based PSCs. In comparison, BTOIC shows an excessive crystallization propensity owing to its oxyalkyl side groups, which eventually leads to a relatively low PCE for the PBDB‐T:BTOIC‐based PSCs. Overall, this work provides insights into the design of novel NIR‐absorbing SMAs for nonfullerene PSCs.     

有机聚合物太阳电池电极的表面性能研究

采用多种方法对有机聚合物电池的电极进行表面处理,在测量接触角的基础上,应用几何平均法计算了电极样品的表面能和极性度,研究了处理方法对电极表面润湿性能的影响。结果表明,电极表面性能与其处理方法密切相关,等离子处理具有最小的接触角、最大的表面能和极性度,有效增强了电极表面的润湿性能,这一结果对于优化电极/活性层的界面性质,改善有机聚合物太阳电池的光伏性能具有非常重要的作用。     

异质结硅太阳能电池a—Si：H薄膜的研究

通过应用Scharfetter-Gummel数值求解Poisson方程，对热平衡态P^ （a-Si:H)/n(c-Si)异质结太阳能电池进行计算机数值模拟分析。结果指出，采用更薄P^ (a-Si：H）薄膜设计能有效增强光生载流子的传输与收集，从而提高a-Si/c-Si异质结太阳能电池的性能。同时，还讨论了P^ (a-Si:h)薄膜中P型掺杂浓度对光生载流了传输与收集的影响。高强茺光照射下模拟，计算表明，a-Si/c-Si异质结结构太阳能电池具有较高光稳定性。     

a-Si/c-Si异质结结构太阳能电池设计分析

通过应用 Scharfetter- Gum mel解法数值求解 Poisson方程 ,对热平衡态 a- Si/ c- Si异质结太阳能电池进行计算机数值模拟分析 ,着重阐述在 a- Si/ c- Si异质结太阳能电池中嵌入 i( a- Si:H)缓冲薄层的作用 ,指出采用嵌入 i( a- Si:H )缓冲薄层设计能有效增强光生载流子的传输与收集 ,从而提高 a- Si/ c- Si异质结太阳能电池的性能 ,同时还讨论 p+ ( a- Si:H)薄膜厚度和 p型掺杂浓度对光生载流子传输与收集的影响 ,而高强度光照射下模拟计算表明 ,a- Si/ c- Si异质结结构太阳能电池具有较高光稳定性