image
Home Journals Journal of Inorganic Materials
Journal of Inorganic Materials

Abbreviation (ISO4): J Inorg Mat      Editor in chief: Lidong CHEN

About  /  Aim & scope  /  Editorial board  /  Indexed  /  Contact  / 
Online first  /  Current issue  /  All issues  /  Top access  /  RSS

Journal of Inorganic Materials >

2024 , Vol. 39 >Issue 4: 359 - 366

DOI: https://doi.org/10.15541/jim20230424

RESEARCH ARTICLE

Influence of Upconversion Luminescent Nanoparticles on Hysteresis Effect and Ion Migration Kinetics in Perovskite Solar Cells

  • Man YU , 1 ,
  • Rongyao GAO 2 ,
  • Yujun QIN 2 ,
  • Xicheng AI , 2
Expand
  • 1. School of Materials Engineering, Xi'an Aeronautical Institute, Xi’an 710077, China
  • 2. Department of Chemistry, Renmin University of China, Beijing 100872, China
AI Xicheng, professor. E-mail:

Received date: 2023-09-18

  Revised date: 2023-11-29

  Online published: 2024-04-25

Supported by

National Natural Science Foundation of China(21903062)

National Natural Science Foundation of China(21973112)

Young Talent Fund of Association for Science and Technology in Shaanxi, China(20220462)

National College Students' Innovation and Entrepreneurship Training Program(202311736016)

Fold

Abstract

Hysteresis effect greatly impacted performance and stability of perovskite solar cells. Ion migration and the resulting accumulation of interface ions were widely recognized as the most important origins. In this study, upconversion luminescent nanoparticles (UCNP) were used to modify the interface of the electron transport layer/perovskite active layer and the intrinsic perovskite active layer, and the effects of UCNP on the morphology, structure, spectral/optoelectronic properties, and ion migration kinetics of perovskite were systematically explored. The results indicated that the device with UCNP modified perovskite active layer has the best photoelectric conversion efficiency (PCE, 16.27%) and significantly improves the hysteresis factor (HF, 0.05). Furthermore, circuit switching transient optoelectronic technology was employed to investigate the ion migration kinetics without interference from photo-generated carriers, revealing the dual role of UCNP in suppressing ion migration and accumulation during the optoelectronic conversion process of perovskite solar cells. On the one hand, UCNP formed barrier layers that hinder ion accumulation. On the other hand, UCNP infiltrated into grain boundaries of perovskite phase during annealing, hindering ion migration and reducing the recovery voltage from 0.43 V to 0.28 V. The mechanism of carriers and ions interaction was explained based on the polarization-induced trap state model to declare the process of UCNP suppressing the hysteresis of perovskite photovoltaic devices. This work provides effective solution for regulating the hysteresis of perovskite solar cells.

Key words： upconversion luminescent nanoparticles; perovskite solar cell; hysteresis effect; ion migration

Cite this article

Man YU , Rongyao GAO , Yujun QIN , Xicheng AI . Influence of Upconversion Luminescent Nanoparticles on Hysteresis Effect and Ion Migration Kinetics in Perovskite Solar Cells[J]. Journal of Inorganic Materials, 2024 , 39(4) : 359 -366 . DOI: 10.15541/jim20230424

利用光伏效应将太阳能转换成电能是获取清洁、廉价、可持续能源的重要途径, 发展新型光伏材料和器件是目前太阳能电池领域的重要方向和研究热点。自20世纪50年代以来, 研究人员已陆续开发出无机半导体太阳能电池、薄膜太阳能电池、染料敏化太阳能电池、有机太阳能电池以及钙钛矿太阳能电池。作为新一代太阳能电池, 有机-无机杂化金属卤化物钙钛矿太阳能电池在过去十几年中光电转换效率(Power Conversion Efficiency, PCE)快速增长, 从3.8%提高到25.7%, 这引起了人们的广泛关注[1⇓⇓⇓-5]。这是由于它们的光电特性优异, 如自由载流子寿命较长、电荷载流子扩散长度优异和缺陷态密度较低[6⇓-8]。然而其还存在一些难以解决的问题。例如, 钙钛矿光伏器件的稳定性不佳[9-10], 以及其特有的迟滞现象[11⇓⇓-14]。迟滞现象是指光伏器件进行电流-电压(Photocurrent-Voltage, J-V)表征时在不同电压扫描方向下(正扫: 低电压→高电压; 反扫: 高电压→低电压) 表现出显著性能差异。此外, 光电性能在很大程度上取决于测试条件, 包括前置条件, 如电或光偏置, 以及测试参数, 如偏置电压扫描速率或范围。多样且不统一的表征方法严重干扰了对钙钛矿光伏器件性能的精准评价, 以及对光电转换机理的深入理解。
根据前人研究结果[15-16], 三个可能引起钙钛矿光伏器件迟滞现象的假设为: 1)载流子在表界面深缺陷中发生慢速捕获和脱捕获过程; 2)钙钛矿活性层铁电极化轴反转; 3)离子迁移。随着研究的深入, 发现钙钛矿材料在室温下的铁电极化率很低不是引起迟滞现象的主要原因, 铁电极化效应逐渐淡出人们视野[17⇓-19]。而修饰钙钛矿活性层化学组成、提高结晶质量或优化各层界面接触、减少体相及表界面缺陷, 可以有效抑制迟滞现象。但随后也有报道发现, 光生载流子在深缺陷的捕获和脱捕获过程与迟滞的时间尺度并不相符[20-21], 而且关于缺陷态的能量分布影响迟滞的内在因素也尚不清楚。因此, 将缺陷作为迟滞现象的原因有一定局限性。
另一方面, 离子迁移被认为是迟滞效应的最可能来源, 这不仅是因为离子扩散与外部电偏压和光照射密切相关[22-23], 还因为钝化离子迁移可以达到抑制迟滞的直接效果[24-25]。例如, 通过界面工程, 在富勒烯衍生物[26⇓-28]和碱金属阳离子[29-30]等一些添加剂的帮助下, 随着光电转换性能提高, 迟滞效应得以抑制或消除。上转换发光材料能将近红外光转换为可见光, 进而提高器件的PCE。目前在钙钛矿太阳能电池体系中, 已有研究报道通过上转换发光材料修饰钙钛矿太阳能电池的介孔层或者介孔层与钙钛矿层的界面[31], 不仅能提高钙钛矿的吸光能力, 还能优化钙钛矿活性层形貌。其中以NaLuF4:20%Yb3+为基质, 以Er3+为发光中心的NaLuF4:20%Yb3+, xEr3+以其独特的发光机制被广泛应用于介孔结构的钙钛矿太阳能电池中。鉴于此, 本工作研究NaLuF4:20%Yb3+, 2%Er3+对平面钙钛矿太阳能电池迟滞效应的影响, 探索其与离子迁移之间的关系, 进而抑制迟滞效应。
本工作将上转换发光材料NaLuF4:20%Yb3+, 2%Er3+作为添加剂引入到电子传输层和钙钛矿活性层的界面及钙钛矿活性层中, 系统探究了其对太阳能电池光电性能的影响。利用回路切换瞬态光电技术(Circuit-switched Transient Photoelectric Technique, cs-TPT), 评价上转换发光材料对光电压建立和离子迁移动力学的作用, 揭示其对钙钛矿太阳能电池迟滞效应影响的机理。

1 实验方法

1.1 钙钛矿太阳能电池的制备

FTO导电玻璃(Pilkington, TEC-7, 7 Ω/sq)分别用洗涤剂、去离子水、丙酮和乙醇超声清洗10 min, 放入等离子清洗机中处理15 min备用。NaLuF4:20%Yb3+, 2%Er3+的制备见补充材料。
电子传输层的制备: 配制0.15 mol/L二(乙酰基)二异丙酮钛的正丁醇溶液作为电子传输层前驱溶液。将1 mg NaLuF4:20%Yb3+, 2%Er3+纳米粒子溶于1 mL正丁醇中, 按体积比2 : 25与电子传输层前驱溶液混合, 作为UCNP处理的电子传输层溶液。分别取40 μL上述电子传输层两种溶液旋涂到不同的FTO基底上, 旋涂条件为4000 r/min, 40 s。将样品在500 ℃马弗炉中煅烧30 min, 分别得到对照组的电子传输层和UCNP修饰的电子传输层。
钙钛矿前驱体溶液的配制: 将PbI2 : CH3NH3I : CH3NH3Cl按照物质的量比1 : 1 : 1溶解于N, N-二甲基甲酰胺(DMF)中, 配制成0.73 mol/L的钙钛矿前驱体溶液; 将1 mg/mL NaLuF4:20%Yb3+, 2%Er3+的DMF溶液和上述钙钛矿前驱体溶液按体积比1 : 10混合得到UCNP处理的钙钛矿前驱体溶液。以上两种钙钛矿前驱体溶液均在室温下搅拌2 h备用。随后分别取45 μL上述两种钙钛矿前驱体溶液分别旋涂于制备好的两种电子传输层上(3500 r/min, 30 s), 最后在100 ℃热台上退火30 min, 得到钙钛矿薄膜。
空穴传输层的制备: 将72.3 mg的2, 2′, 7, 7′-四[N, N-二(4-甲氧基苯基)氨基]-9, 9′-螺二芴溶解在 1 mL氯苯中, 向其中加入28.8 μL的4-叔丁基吡啶和17.5 μL 520 mg/mL双-(三氟甲磺酰基)亚胺锂的乙腈溶液。然后取35 μL该空穴传输层前驱溶液旋涂在钙钛矿层上(3500 r/min, 30 s)。
电极蒸镀: 采用真空蒸镀仪在空穴传输层上蒸镀80 nm Au层, 蒸镀速度为0.01 nm/s。

1.2 表征

使用场发射扫描电子显微镜(SEM, Hitachi SU8010)在3 kV加速电压和10 μA电流下表征钙钛矿薄膜的表面形貌。采用X射线衍射仪(XRD, Shimadzu XRD-7000, Cu Kα, 2θ=10°~80°, 扫描速率2 (°)/min)进行晶体衍射分析。样品的紫外-可见吸收光谱(UV-Vis)采用Agilent Cary 60紫外-可见分光光度计测定; 使用FLS980 (Edinburgh)光谱仪测定钙钛矿薄膜的稳态荧光光谱和时间分辨荧光光谱, 激发波长为475 nm, 检测波长为770 nm。器件J-V特征曲线是在AM 1.5G (100 mW/cm)光照条件下通过Keithley 2400数字源表获取, 测量范围-0.3~1.3 V, 测试前未进行任何光电预处理。

1.3 瞬态光电测试

cs-TPT实验装置和详细的时间时序如补充材料图S1所示, 包括开路光电压建立(Open Circuit Voltage Build-up, OCVB)、开路光电压衰减(Open Circuit Voltage Decay, OCVD)、时间分辨电荷抽取(Time-Resolved Charge Extraction, TRCE)和光电压恢复四个不同的阶段。cs-TPT从成熟的TRCE技术[32-34]发展而来, 而cs-TPT的时间序列通过更精心的编程, 用于在一个测试周期内进行多电路切换。详细地说, 钙钛矿太阳能电池与互补金属氧化物半导体(Complementary Metal Oxide Semiconductor， CMOS)开关(额定栅极电压(VG): 2.4 V, 响应时间: ~4 ns, 固有电阻: 50 Ω)和数字示波器(耦合电阻: 1 MΩ, Lecroy, HDO4054A)并联, 被脉冲激光束照射, 其中泵浦功率由中性密度滤波器(大恒光学, GCO-074M)精确调节, 由示波器实时记录时间分辨光电信号。数字延时发生器(Stanford Research Systems, DG535)用于调制脉冲激光器(补充材料图S1), 并控制激光器、示波器与CMOS开关的VG 之间的同步。具体而言, 当VG (2.4 V)施加在CMOS开关上或从CMOS开关移除时, 样品总电阻(RS)为50 Ω或1 MΩ。因此, 电路可以在短路状态和开路状态之间快速切换, 响应时间快至4 ns。测量OCVB和OCVD时, 器件被照射约5 s, 直到光电压达到常数, 然后关闭激光器。在OCVD的指定时间, DG535输出2.4 V偏置电压, 该电压施加在CMOS开关上, 用于测量TRCE, 停留时间约为20 μs, 随后去除偏置电压以产生光电压恢复信号。

2 结果与讨论

图1(a)为经典的钙钛矿太阳能电池结构示意图, 包括FTO基底、电子传输层(Electron Transport Layer, ETL)、钙钛矿活性层(Perovskite, PVK)、空穴传输层(Hole Transport Layer, HTL)和Au电极。图1(b)为本工作采用的上转换发光材料NaLuF4:20%Yb3+, 2%Er3+纳米粒子的结构示意图, 其TEM和XRD表征结果见补充材料图S2。本工作尝试将其用于修饰钙钛矿太阳能电池的ETL和PVK, UCNP无论是修饰ETL还是PVK, 用980 nm波长激光激发, 均观察到绿光, 如补充材料图S3和图S4所示, 说明UCNP确实均匀融入到ETL和PVK中。后续讨论将对照组器件标记为Compact/PVK, UCNP修饰ETL的器件标记为UCNP+Compact/PVK, UCNP仅仅掺杂到PVK的器件标记为Compact/PVK+UCNP, UCNP同时修饰ETL和PVK的器件标记为UCNP+Compact/PVK+UCNP。
图1 (a)钙钛矿太阳能电池的和(b) UCNP的结构示意图

Fig. 1 Schematic diagrams of structures of (a) perovskite solar cells and (b) UCNP

2.1 UCNP对钙钛矿薄膜形貌和结构的影响

首先利用SEM表征所制备的钙钛矿薄膜的表面形貌, 如图2所示。图2(a)为对照组Compact/PVK的形貌, 其中未修饰的钙钛矿为块状薄片。图2(b)中UCNP修饰ETL后块状钙钛矿薄片变得更大更致密。当UCNP掺杂在PVK中制备Compact/PVK+UCNP时, 则得到如图2(c)的鹅卵石状结构的表面形貌。而当UCNP同时修饰ETL和PVK时, 如图2(d)所示, 所获得的PVK主要由小块状紧密堆叠而成且具有较为明显的晶界。这说明UCNP无论是修饰ETL还是直接引入到PVK中, 均能优化钙钛矿的形貌, 但同时修饰两者时, 钙钛矿薄膜的质量反而比对照组低。
图2 (a) Compact/PVK、(b) UCNP+Compact/PVK、(c) Compact/ PVK+UCNP和(d) UCNP+Compact/PVK+UCNP的SEM照片

Fig. 2 SEM images of (a) Compact/PVK, (b) UCNP+ Compact/PVK, (c) Compact/PVK+UCNP, and (d) UCNP+ Compact/PVK+UCNP

四种钙钛矿薄膜的XRD图谱如图3所示, 所有样品均在2θ=14.7°和29.0°附近出现相同的主衍射峰, 分别对应四方钙钛矿的(110)和(220)晶面[35-36]。四种钙钛矿薄膜的XRD图谱没有明显差异, 表明无论UCNP修饰ETL、PVK或者同时修饰ETL和PVK, 均未改变钙钛矿的晶体结构。
图3 Compact/PVK、UCNP+Compact/PVK、Compact/PVK+ UCNP和UCNP+Compact/PVK+UCNP的XRD图谱

Fig. 3 XRD patterns of Compact/PVK, UCNP+Compact/PVK, Compact/PVK+UCNP, and UCNP+Compact/PVK+UCNP samples

2.2 UCNP对钙钛矿薄膜光谱性能的影响

基于石英基底的本征钙钛矿薄膜和UCNP修饰的钙钛矿薄膜在紫外-可见光到近红外区域呈现出几乎相同的吸收强度和轮廓, 且稳态荧光发光峰均在775 nm附近, 如图4(a)所示。进一步通过时间分辨荧光光谱探究UCNP对钙钛矿薄膜的影响(图4(b)), 其中UCNP调控的钙钛矿薄膜均比对照组(Compact/PVK)的荧光寿命更短, 表明UCNP无论修饰ETL还是修饰PVK均可以提高ETL和PVK界面间的电荷收集能力。对四种薄膜的荧光衰减曲线进行拟合分析发现, UCNP+Compact/ PVK(~6.7 ns)和Compact/PVK+UCNP(10.1 ns)的荧光寿命较短, 而UCNP+Compact/PVK+UCNP (18.8 ns)的荧光寿命延长, 说明UCNP同时修饰ETL和PVK时, 并未达到加倍的效果, 这可能与UCNP的引入量过多导致界面接触变差有关。根据初步的光谱结果推测, 引入UCNP并未改变钙钛矿薄膜的本征光谱属性, 但是对界面电荷的分离和转移起到了促进作用。
图4 (a)基于石英基底的本征钙钛矿薄膜的紫外-可见吸收光谱和稳态荧光光谱图, 以及(b)四种钙钛矿薄膜样品的时间分辨荧光光谱图

Fig. 4 (a) UV-Vis absorption and steady-state fluorescence spectra of perovskite films deposited on quartz substrates, and (b) time resolved fluorescence spectra of four perovskite thin films

2.3 UCNP对钙钛矿太阳能电池性能的影响

利用上述四种钙钛矿薄膜制备完整的钙钛矿太阳能电池, 分别测试其光电转换性能，获得的J-V曲线如图5所示。对照组钙钛矿电池的J-V曲线(图5(a))的正反扫曲线偏离较大, 迟滞现象严重。所对应的填充因子(FF)相差较大, 反扫条件下FF为63.45%, 正扫条件下FF降到44.13%, 导致该电池的正反扫PCE相差很大, 分别为7.20%和12.36%。UCNP修饰的钙钛矿太阳能电池的J-V曲线(图5(b~d))中, 正反扫曲线偏离情况得到明显改善, 迟滞效应得到明显抑制。四种钙钛矿太阳能电池的详细光伏性能参数见表1。其中迟滞因子HF计算公式[37-38]: HF= (Areverse-Aforward)/Areverse, 其中, A表示电压积分范围为0至VOC的相应J-V曲线的积分面积, 下标表示不同的扫描方向。为了保障实验的重复性和可靠性, 分别统计每种电池的10个器件的正反扫PCE及HF, 数据见补充材料图S5和表S1, 验证了数据的可靠性。对比发现, UCNP仅修饰PVK的器件的PCE最高(16.27%)。然而UCNP+Compact/PVK+ UCNP器件的PCE反而减低, 结合钙钛矿薄膜表面形貌(图2)和时间分辨荧光光谱图(图4), 可以推论UCNP同时修饰ETL和PVK的表/界面会导致表/界面接触变差, 造成UCNP+Compact/PVK+UCNP的光电流密度明显降低, 但与对照组相比迟滞现象仍然得到明显抑制。
图5 (a) Compact/PVK、(b) UCNP+Compact/PVK、(c) Compact/PVK+UCNP和(d)UCNP+Compact/PVK+UCNP钙钛矿太阳能电池在正扫和反扫条件下的最佳J-V曲线

Fig. 5 J-V curves under forward and reverse scanning conditions for perovskite solar cells with champion performances of (a) Compact/PVK, (b) UCNP+Compact/PVK, (c) Compact/PVK+UCNP, and (d) UCNP+Compact/PVK+UCNP

表1 四种钙钛矿器件正反扫条件下的光伏参数及HF

Table 1 Photovoltaic parameters and hysteresis factors (HF) of four perovskite devices upon forward and reverse scanning conditions

Sample Scan direction Open-circuit voltage/
mV		 Short-circuit current/
(mA·cm-2)		 FF/% PCE/% HF
Compact/PVK Reverse 996 19.56 63.45 12.36 0.42
Forward 912 17.89 44.13 7.20
UCNP+Compact/PVK Reverse 1038 20.37 0.74 15.65 0.07
Forward 1045 19.84 0.70 14.52
Compact/PVK+UCNP Reverse 1034 20.96 0.75 16.27 0.05
Forward 1032 20.39 0.73 15.37
UCNP+Compact/PVK+UCNP Reverse 1016 18.31 0.66 12.28 0.15
Forward 976 17.76 0.60 10.40

2.4 UCNP对钙钛矿太阳能电池离子迁移动力学的影响

为进一步探究UCNP影响钙钛矿太阳能电池迟滞性的机制, 利用本课题组设计开发的cs-TPT技术(补充材料图S1)研究了四种钙钛矿电池的载流子和离子迁移行为。图6(a)展示了光电压建立和时间的关系, 时间尺度从微秒持续到秒量级, 其中微秒和毫秒量级的快过程被认为是“自由”载流子的布居[24]。而秒量级动力学则被认为是和离子迁移相关的载流子的布居, 即这个较慢的动力学过程对应离子迁移。进一步, 采用cs-TPT获得的恢复电压信号分析离子迁移的行为。根据极化诱导缺陷模型(Polarization- Induced Trap State, PITS)[39⇓⇓-42], 恢复电压(Recovery Voltage, Vr)来源于PITS捕获的光生电子, 即当电荷抽取完成时将电路从短路切换成开路时, PITS捕获的光生电子被释放, 形成Vr, 所以可以通过Vr的最大值来评估极化诱导缺陷态的密度。如图6(b)所示, UCNP+Compact/PVK和Compact/PVK+ UCNP电池的Vr分别为0.36和0.28 V, 均比对照组(0.43 V)低, 表明UCNP不仅能有效抑制ETL和PVK的离子累积, 且能钝化PVK中的离子迁移, 进而降低极化诱导缺陷态密度。
图6 不同钙钛矿太阳能电池的(a)开路光电压上升曲线和(b) cs-TPT动力学曲线

Fig. 6 (a) Open-circuit photovoltage buildup curves and (b) cs-TPT kinetics curves of different perovskite solar cells

cs-TPT结果与器件性能相结合可以合理解释UCNP修饰钙钛矿的表/界面进而抑制迟滞现象的原理。如图7(a)所示, 迁移离子在界面累积形成的PITS会捕获/脱捕获光生电子, 图中Vr表示PITS脱捕获光生电子产生的恢复电压, 波浪曲线箭头表示阳离子迁移过程。如图7(b)所示, UCNP修饰ETL在电子传输层/钙钛矿界面处形成阻隔层, 减小界面离子累积, 钝化PITS。同理, 当UCNP修饰PVK时, UCNP渗透到钙钛矿晶界处, 阻碍离子迁移通道, 降低PITS密度。因此, UCNP+Compact/ PVK和Compact/PVK+UCNP器件的Vr明显降低, 迟滞效应得到显著改善。
图7 UCNP抑制离子迁移机制

Fig. 7 Mechanism of UCNP inhibiting ion migration

(a) Control group and (b) UCNP regulated perovskite solar cells

3 结论

本研究利用上转化发光材料修饰经典平面钙钛矿太阳能电池的表/界面, 并通过OCVB和cs-TPT技术表征载流子动力学、界面离子积累和离子迁移过程及其对钙钛矿太阳能电池迟滞效应的影响。研究发现, 引入UCNP并未改变本征钙钛矿的晶体结构、吸收光谱和荧光光谱范围, 但能显著提高界面电荷收集能力, 在优化器件性能的同时显著改善迟滞性。其中Compact/PVK+UCNP电池的性能最佳, PCE达到16.27%, HF为0.05。OCVB结果说明引入UCNP能抑制离子迁移, 进而改善光电压建立过程。cs-TPT结果显示Compact/PVK+UCNP的Vr为0.28 V, 比对照组(0.43 V)降低了35%。极化诱导缺陷态模型揭示了UCNP修饰表/界面, 同时起到了抑制离子迁移和累积的双重作用: 一方面UCNP修饰ETL在界面处起到阻隔层的作用; 另一方面UCNP修饰PVK, 渗入钙钛矿晶界, 抑制离子迁移通道, 阻碍离子在钙钛矿层中的迁移。在双重作用下, 钙钛矿电池的迟滞效应得到显著改善。本工作为制备高效率稳定的钙钛矿光伏器件提供了一种有效的调控方法。

补充材料

本文相关补充材料可登录 https://doi.org/10.15541/jim20230424查看。
上转换发光材料对钙钛矿太阳能电池迟滞效应和离子迁移动力学的影响
于嫚1, 高荣耀2, 秦玉军2, 艾希成2
(1. 西安航空学院 材料工程学院, 西安 710077; 2. 中国人民大学 化学系, 北京 100872)
上转换发光材料的制备: 使用传统的溶剂热方法制备NaLuF4:20%Yb3+, 2%Er3+。首先, 将7 mL油酸和15 mL十八烯加入到100 mL三颈烧瓶中; 然后, 将LuCl3:ErCl3:YbCl3 按物质的量比78:20:2加入至烧瓶中, 在氩气气氛下加热至160 ℃, 得到透明溶液。冷却至室温后, 将4 mL含有NaOH(2.5 mmol)和NH4F(4 mmol)的甲醇溶液分别加入至这些烧瓶中, 并在真空下搅拌30 min。随后, 将溶液在氩气气氛下加热至295 ℃, 1 h, 以获得Er3+物质的量掺杂浓度为2%的NaLuF4:20%Yb3+, 2%Er3+。将过量乙醇倒入所得溶液中, 自然冷却至室温后分离产物, 并用乙醇和环己烷反复洗涤产物三次。将获得的白色NaLuF4:20%Yb3+, 2%Er3+在真空下干燥。
NaLuF4:20%Yb3+, 2%Er3+的表征: 使用透射电子显微镜(TEM，JEOL JEM-2010)在200 kV下测定纳米颗粒的形貌。将制备的样品分散在环己烷或乙醇中, 并滴加到铜格栅表面, 进行TEM分析。使用岛津7000 X射线衍射仪以2 (°)/min的扫描速率在2θ=10°~80°的范围内进行粉末XRD测试(Cu Kα辐射, λ=1.54 Å)。
通过TEM和XRD对NaLuF4:20%Yb3+, 2%Er3+的形貌和结构分别进行了表征, 如图S2所示。NaLuF4:20%Yb3+, 2%Er3+样品显示出均匀的球形形貌(图S2(a)), 且其XRD数据与JCPDS卡(No.27-0726)吻合度较高, 具体晶面标注如图S2(b)所示。
图S1 (a) cs-TPT装置示意图[1](ND filter: neutral density filter, DUT: device under test, Sync.: synchronizing, Trig.: trigger, Sig. = signal); (b)典型cs-TPT设置(Trigger, Laser, VG, and RS)的时间序列

Fig. S1 (a) Schematic illustration of the cs-TPT setup ](ND filter: neutral density filter, DUT: device under test, Sync.: synchronizing, Trig.: trigger, Sig.= signal); (b) Time sequences of typical cs-TPT settings (Trigger, Laser, VG, and RS)

图S2 NaLuF4:20%Yb3+, 2%Er3+的(a)TEM照片和(b)XRD图谱

Fig. S2 (a) TEM image and (b) XRD pattern of NaLuF4:20%Yb3+, 2%Er3+

图S3 980 nm 激光照射(a) UCNP+Compact和(b) PVK+ UCNP的混合溶液

Fig. S3 Mixed solutions of (a) UCNP+Compact and (b) PVK+ UCNP irradiated with 980 nm laser

图S4 980 nm激光照射(a) UCNP+Compact/PVK、(b) Compact/PVK+UCNP和(c) UCNP+Compact/PVK+UCNP的照片

Fig. S4 Pictures of (a) UCNP+Compact/PVK, (b) Compact/PVK+UCNP and (c) UCNP+Compact/PVK+UCNP irradiated with 980 nm laser

不同器件的正反扫效率及HF统计数据如图S5所示, 不难发现四种电池的PCEreverse和PCEforward误差棒偏离平均值程度均较小。结合表S1分析, 四种电池的统计数据的方差均小于1, 说明四种电池的重复性较好。根据HF=(Areverse-Aforward)/Areverse计算获得的HF的方差更小(<0.02), 进一步验证了数据的可靠性和重复性。
图S5 不同器件的正反扫PCE及HF统计数据

Fig. S5 PCE and HF statistical data of different devices under forward and reverse scanning

表S1 四种电池的HF和正反扫条件下的PCE的方差

Table S1 HF and variance of PCE under forward and reverse scanning conditions of cells

Sample S2(PCEreverse) S2(PCEforward) S2(HF)
Compact/PVK 0.55956 0.58046 0.01156
UCNP+Compact/PVK 0.41318 0.40968 0.01130
Compact/PVK+UCNP 0.25838 0.33691 0.00810
UCNP+Compact/PVK+UCNP 0.19304 0.96262 0.01451
参考文献:
[1] YUAN S, WANG H Y, LOU F G, et al. Polarization-induced trap states in perovskite solar cells revealed by circuit-switched transient photoelectric technique. Journal of Physical Chemistry C, 2022, 126(7): 3696.

References

Publishing order | Descend order by publishing year | Descend order by cited within
[1]
KOJIMA A, TESHIMA K, SHIRAI Y, et al. Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. Journal of the American Chemical Society, 2009, 131(17): 6050.

DOI PMID

[2]
LEE M M, TEUSCHER J, MIYASAKA T, et al. Efficient hybrid solar cells based on meso-superstructured organometal halide perovskites. Science, 2012, 338(6107): 643.

DOI PMID

[3]
KIM M, JEONG J, LU H, et al. Conformal quantum dot-SnO2 layers as electron transporters for efficient perovskite solar cells. Science, 2022, 375(6578): 302.

DOI

[4]
JIANG Q, TONG J, XIAN Y, et al. Surface reaction for efficient and stable inverted perovskite solar cells. Nature, 2022, 611(7935): 278.

DOI

[5]
PARK J, KIM J, YUN H S, et al. Controlled growth of perovskite layers with volatile alkylammonium chlorides. Nature, 2023, 616: 724.

DOI

[6]
SAVENIJE T J, PONSECA C S, KUNNEMAN L, et al. Thermally activated exciton dissociation and recombination control the carrier dynamics in organometal halide perovskite. Journal of Physical Chemistry Letters, 2014, 5(13): 2189.

DOI PMID

[7]
SHI D, ADINOLFI V, COMIN R, et al. Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals. Science, 2015, 347(6221): 519.

DOI

[8]
SUM T C, MATHEWS N, XING G, et al. Spectral features and charge dynamics of lead halide perovskites: origins and interpretations. Accounts of Chemical Research, 2016, 49(2): 294.

DOI PMID

[9]
LI Q, ZHENG Y C, WEI Z P, et al. Halide diffusion equilibrium and its impact on efficiency evolution of perovskite solar cells. Advanced Energy Materials, 2022, 12(48): 2202982.

DOI

[10]
HE J J, LIU J X, HOU Y, et al. Surface chelation of cesium halide perovskite by dithiocarbamate for efficient and stable solar cells. Nature Communications, 2020, 11: 4237.

DOI PMID

[11]
SHAO Y H, XIAO Z G, BI C, et al. Origin and elimination of photocurrent hysteresis by fullerene passivation in CH3NH3PbI3 planar heterojunction solar cells. Nature Communications, 2014, 5: 5784.

DOI

[12]
LIU S, GUAN Y J, SHENG Y S, et al. A review on additives for halide perovskite solar cells. Advanced Energy Materials, 2019, 10(13): 1902492.

DOI

[13]
KANG D H, PARK N G. On the current-voltage hysteresis in perovskite solar cells: dependence on perovskite composition and methods to remove hysteresis. Advanced Materials, 2019, 31(34): 1805214.

DOI

[14]
KE W J, XIAO C X, WANG C L, et al. Employing lead thiocyanate additive to reduce the hysteresis and boost the fill factor of planar perovskite solar cells. Advanced Materials, 2016, 28(26): 5214.

DOI

[15]
LIU P Y, WANG W, LIU S M, et al. Fundamental understanding of photocurrent hysteresis in perovskite solar cells. Advanced Energy Materials, 2019, 9(13): 1803017.

DOI

[16]
FROST J M, WALSH A. What is moving in hybrid halide perovskite solar cells? Accounts of Chemical Research, 2016, 49(3): 528.

DOI PMID

[17]
ROTHMANN M U, LI W, ZHU Y, et al. Direct observation of intrinsic twin domains in tetragonal CH3NH3PbI3. Nature Communications, 2017, 8: 14547.

DOI

[18]
KENNARD R M, DAHLMAN C J, DECRESCENT R A, et al. Ferroelastic hysteresis in thin films of methylammonium lead iodide. Chemistry of Materials, 2021, 33: 298.

DOI

[19]
WEI J, ZHAO Y, LI H, et al. Hysteresis analysis based on the ferroelectric effect in hybrid perovskite solar cells. Journal of Physical Chemistry Letters, 2014, 5(21): 3937.

DOI PMID

[20]
MIYANO K, YANAGIDA M, TRIPATHI N, et al. Hysteresis, stability, and ion migration in lead halide perovskite photovoltaics. Journal of Physical Chemistry Letters, 2016, 7(12): 2240.

DOI PMID

[21]
BI E, CHEN H, XIE F, et al. Diffusion engineering of ions and charge carriers for stable efficient perovskite solar cells. Nature Communications, 2017, 8: 15330.

DOI PMID

[22]
XIA G Z, HUANG B Y, ZHANG Y, et al. Nanoscale insights into photovoltaic hysteresis in triple-cation mixed-halide perovskite: resolving the role of polarization and ionic migration. Advanced Materials, 2019, 31(36): 1902870.

DOI

[23]
LIAN X M, ZUO L J, CHEN B W, et al. Light-induced beneficial ion accumulation for high-performance quasi-2D perovskite solar cells. Energy Environmental Science, 2022, 15(6): 2499.

DOI

[24]
LOU F, YUAN S, WANG X, et al. Distinguishing the migration time scale of ion species in perovskite solar cells. Chemical Physics Letters, 2022, 796: 139570.

DOI

[25]
WANG H Y, ZHAO J S, LI Y S, et al. Diffusion dynamics of mobile ions hidden in transient optoelectronic measurement in planar perovskite solar cells. ACS Applied Energy Materials, 2020, 3(9): 8330.

DOI

[26]
ZHONG Y, HUFNAGEL M, THELAKKAT M, et al. Role of PCBM in the suppression of hysteresis in perovskite solar cells. Advanced Functional Materials, 2020, 30(23): 1908920.

DOI

[27]
LI J X, MENG X C, HUANG Z Q, et al. A regularity-based fullerene interfacial layer for efficient and stable perovskite solar cells via blade-coating. Advanced Functional Materials, 2022, 32(1): 2105917.

DOI

[28]
YU M, WANG H Y, ZHAO J S, et al. The influence of fullerene on hysteresis mechanism in planar perovskite solar cells. Chemical Physics Letters, 2020, 750: 137443.

DOI

[29]
LI C, WANG A, XIE L, et al. Emerging alkali metal ion (Li+, Na+, K+ and Rb+) doped perovskite films for efficient solar cells: recent advances and prospects. Journal of Materials Chemistry A, 2019, 7(42): 24150.

DOI

[30]
ZHAO Y P, YAVUZ I, WANG M H, et al. Suppressing ion migration in metal halide perovskite via interstitial doping with a trace amount of multivalent cations. Nature Materials, 2022, 21(12): 1396.

DOI

[31]
LIANG T, FU M, LI M, et al. Application of upconversion photoluminescent materials in perovskite solar cells: opportunities and challenges. Materials Today Energy, 2021, 21: 100740.

DOI

[32]
WANG Y, WANG H Y, HAN J, et al. The influence of structural configuration on charge accumulation, transport, recombination, and hysteresis in perovskite solar cells. Energy Technology, 2017, 5(3): 442.

DOI

[33]
WANG Y, WANG H Y, YU M, et al. Trap-limited charge recombination in intrinsic perovskite film and meso-superstructured perovskite solar cells and the passivation effect of the hole-transport material on trap states. Physical Chemistry Chemical Physics, 2015, 17(44): 29501.

DOI PMID

[34]
WANG Y, WU D P, FU L M, et al. Density of state determination of two types of intra-gap traps in dye-sensitized solar cell and its influence on device performance. Physical Chemistry Chemical Physics, 2014, 16(23): 11626.

DOI

[35]
KIM J Y, LEE J W, JUNG H S, et al. High-efficiency perovskite solar cells. Chemical Reviews, 2020, 120(15): 7867.

DOI PMID

[36]
WANG W, ZHOU J, TANG W. Passivation strategies of perovskite film defects for solar cells. Journal of Inorganic Materials, 2021, 37(2): 129.

DOI

[37]
KIM H S, JANG I H, AHN N, et al. Control of I-V hysteresis in CH3NH3PbI3 perovskite solar cell. Journal of Physical Chemistry Letters, 2015, 6(22): 4633.

DOI

[38]
NEMNES G A, BESLEAGE C, STANCU V, et al. Normal and inverted hysteresis in perovskite solar cells. Journal of Physical Chemistry C, 2017, 121(21): 11207.

DOI

[39]
YUAN S, WANG H Y, LOU F G, et al. Polarization-induced trap states in perovskite solar cells revealed by circuit-switched transient photoelectric technique. Journal of Physical Chemistry C, 2022, 126(7): 3696.

DOI

[40]
YUAN S, LOU F G, LI Y Y, et al. Targeted suppression of hysteresis effect in perovskite solar cells through the inhibition of cation migration. Applied Physics Letters, 2023, 122(13): 133502.

DOI

[41]
MIAO S, YUAN S, ZHU D, et al. Mesoporous TiO2 layer suppresses ion accumulation in perovskite solar cells. Physical Chemistry Chemical Physics, 2022, 24(35): 20689.

DOI

[42]
LI Y Y, YUAN S, MIAO S S, et al. Uncovering the influence of cation composition engineering on the ion migration kinetics in perovskite solar cells. Journal of Physical Chemistry C, 2023, 127(30): 14679.

DOI

Options
Outlines

/

〈 〉