Lead-free double perovskite Cs_(2)AgBiBr_(6) has gained increasing attention recently.However,the power conversion efficiency(PCE)of Cs_(2)AgBiBr_(6) perovskite solar cells(PSCs)is still low compared with their lead-b...Lead-free double perovskite Cs_(2)AgBiBr_(6) has gained increasing attention recently.However,the power conversion efficiency(PCE)of Cs_(2)AgBiBr_(6) perovskite solar cells(PSCs)is still low compared with their lead-based counterparts.Here,by using photoluminescence(PL),time-resolved photoluminescence(TRPL),and ultrafast transient absorption(TA)measurements,the unbalance between the electron and hole in diffusion and transfer,which limits the performance of the Cs_(2)AgBiBr_(6) PSCs,was further revealed.Considering this issue,a strategy of using the mesoporous TiO_(2) electron transport layer(ETL)to construct a bulk heterojunction in Cs_(2)AgBiBr_(6) PSCs was proposed.Consequently,the PCE had improved by over 24%comparing with that only used compact TiO_(2) ETL.Moreover,based on mesoporous TiO_(2),the unencapsulated Cs_(2)AgBiBr_(6) PSCs maintained 90%of their initial performance after approximately 1200 h of storage in a desiccator(humidity~30%).This work gives further understanding of Cs_(2)AgBiBr_(6) perovskite and demonstrates that a proper design of balancing the electron and hole diffusion can improve device performance.展开更多
光催化因其可以利用太阳能进行光解水产氢、CO_(2)还原、降解有机污染物及有机物转化而被认为是解决当前能源危机和环境问题的一种有效手段.由于光催化反应是由光激发光催化材料生成光生载流子引发的,因此理想的光催化剂应当具有宽的光...光催化因其可以利用太阳能进行光解水产氢、CO_(2)还原、降解有机污染物及有机物转化而被认为是解决当前能源危机和环境问题的一种有效手段.由于光催化反应是由光激发光催化材料生成光生载流子引发的,因此理想的光催化剂应当具有宽的光响应范围、低的光生载流子复合率和足够的氧化还原能力来进行表面反应.然而单一组分的半导体材料难以同时满足宽光谱响应(即窄带隙)和强氧化还原能力(即价带更正和导带更负).通过耦合两个具有可见光响应且交错能带排布的半导体来构建S型异质结,不仅能拓宽光催化剂的光吸收范围、促进电荷分离,还同时保留了两种半导体的强氧化还原能力,是发展高效光催化材料的一种有效途径.Cs_(2)AgBiBr_(6)的导带和价带分别位于–0.65 V vs.NHE和1.60 V vs.NHE,而Bi_(2)WO_(6)的导带和价带分别为–0.4 V vs.NHE和2.4 V vs.NHE,两者能带位置匹配.因此,本文选择Cs_(2)AgBiBr_(6)和Bi_(2)WO_(6)用于构建S型异质结复合材料,采用超声辅助方法处理含有Cs_(2)AgBiBr_(6)量子点和Bi_(2)WO_(6)微米花的乙酸乙酯溶液,通过在Cs_(2)AgBiBr_(6)量子点和Bi_(2)WO_(6)微米花界面间形成Bi–Br键,组装出了Cs_(2)AgBiBr_(6)量子点/Bi_(2)WO_(6)微米花异质结复合材料,并考察了材料在可见光照射下还原CO_(2)的光催化活性.结果表明,所制备的Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6)异质结复合材料具有优越的光催化还原CO_(2)生成CO和CH4性能,发现在一系列含有不同比例的x Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6)异质结复合材料中(x为Cs_(2)AgBiBr_(6)与Bi_(2)WO_(6)的质量比,x=0.2,0.5,1.0),0.5 Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6)异质结复合材料表现出最优的光催化性能,在300 W氙灯(420 nm≤λ≤800 nm)照射下8 h内生成了15.4μmol g–1的CO和3.2μmol g–1的CH4.其性能明显优于同等反应条件下单纯Cs_(2)AgBiBr_(6),Bi_(2)WO_(6)以及等比例机械混合的Cs_(2)AgBiBr_(6)和Bi_(2)WO_(6)的光催化活性,这归因于Cs_(2)AgBiBr_(6)和Bi_(2)WO_(6)间形成了有效的S型异质结,该S型异质结可在不牺牲Bi_(2)WO_(6)价带空穴氧化能力和Cs_(2)AgBiBr_(6)导带电子还原能力的基础上,促进光生电子-空穴对的分离.综上,本文结果表明耦合两种具有交错能带的光催化材料来形成S型异质结是开发高效光催化剂的一种有效策略,也展示了无铅钙钛矿在光催化中的应用前景.展开更多
In recent years, limited photocatalysis efficiency and wide band gap have hindered the application of TiO_(2) in the field of photocatalysis. A leading star in photocatalysis has been revealed as lead-free Cs_(2)AgBiB...In recent years, limited photocatalysis efficiency and wide band gap have hindered the application of TiO_(2) in the field of photocatalysis. A leading star in photocatalysis has been revealed as lead-free Cs_(2)AgBiBr_(6) double halide perovskite nanocrystals, owing to its strong visible light absorption and tunable band gap. In this work, this photocatalytic process was facilitated by a unique TiO_(2)/Cs_(2)AgBiBr_(6) composite, which was identified as an S-cheme heterojunction. TiO_(2)/Cs_(2)AgBiBr_(6) composite was investigated for its structure and photocatalytic behavior. The results showed that when the perovskite dosage is 40%, the photocatalytic rate of TiO_(2) could be boosted to 0.1369 min^(-1). This paper discusses and proposes the band gap matching, carrier separation, and photocatalytic mechanism of TiO_(2)/Cs_(2)AgBiBr_(6) composites, which will facilitate the generation of new ideas for improving TiO_(2)’s photocatalytic performance.展开更多
The valence band offset between Cs_(2)AgBiBr_(6)and hole transport layer(HTL)is approximately 1.00 e V,which results in high energy loss and is identified as one of the bottle necks of Cs_(2)Ag BiBr_(6)perovskite sola...The valence band offset between Cs_(2)AgBiBr_(6)and hole transport layer(HTL)is approximately 1.00 e V,which results in high energy loss and is identified as one of the bottle necks of Cs_(2)Ag BiBr_(6)perovskite solar cell(PSC)for achieving high power conversion efficiency(PCE).To tackle this problem,we propose the optimization of the energy level alignment by designing and synthesizing novel deep-level hole transport materials(HTMs).The sole introduction of deep-level HTMs successfully reduces the valence band offset between Cs_(2)Ag Bi Br_(6)and HTL,but induces the increased valence band offset at HTL/Au interface,limiting the PCE improvement.To further solve the problem and improve the PCE,the gradient energy level arrangement is constructed by combining the newly developed deep-level HTM 6,6’-(3-((9,9-dimethyl-9H-fluoren-3-yl)(4-methoxyphenyl)amino)thiophene-2,5-diyl)bis(N-(9,9-dimethyl-9H-fluoren-2-yl)-N,9-bis(4-methoxyphenyl)-9H-carbazol-3-amine)(TF)with 2,2’,7,7’-tetrakis(N,N’-dipmethoxyphenylamine)-9,9-spirobifluorene(Spiro-OMeTAD).Through optimization,an impressive PCE of 3.50%with remarkably high open-circuit voltage(V_(oc))and fill factor(FF)is achieved,qualifying it among the best pristine Cs_(2)AgBiBr_(6)PSCs.展开更多
无铅双钙钛矿由于具有较好的稳定性和无毒的特点吸引了很多学者的目光,有希望成为下一代光伏和光电子材料.然而,目前其光电器件性能并不理想.我们报道了一个简单的溶液法用于制备无机双钙钛矿Cs_(2)AgBiBr_(6)和MA_(2)AgBiBr_(6)微米片...无铅双钙钛矿由于具有较好的稳定性和无毒的特点吸引了很多学者的目光,有希望成为下一代光伏和光电子材料.然而,目前其光电器件性能并不理想.我们报道了一个简单的溶液法用于制备无机双钙钛矿Cs_(2)AgBiBr_(6)和MA_(2)AgBiBr_(6)微米片.与传统的溶液旋涂法相比,这种方法得到的Cs_(2)AgBiBr_(6)和MA_(2)Ag Bi Br_(6)微米片具有很好的结晶性.将它们做成光电探测器后,其响应度达到了245 mA W^(-1),比旋涂法制备的器件高出两个量级,且响应时间为145μs.热稳定性研究表明,将Cs_(2)AgBiBr_(6)器件在空气中加热到160℃再回到室温,其光电响应并没有受到影响.这些结果表明,溶液法制备无铅双钙钛矿具有更广阔的应用前景.展开更多
基金financial support from Macao Science and Technology Development Fund,China(FDCT-0044/2020/A1,FDCT-091/2017/A2,FDCT-014/2017/AMJ)University of Macao Research Grant,China(MYRG2018-00148-IAPME,MYRG2018-00142-IAPME)from University of Macao+2 种基金the Natural Science Foundation of China,China(91733302,61935017)Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials(2019B121205002)Natural Science Foundation of Guangdong Province,China(2019A1515012186).
文摘Lead-free double perovskite Cs_(2)AgBiBr_(6) has gained increasing attention recently.However,the power conversion efficiency(PCE)of Cs_(2)AgBiBr_(6) perovskite solar cells(PSCs)is still low compared with their lead-based counterparts.Here,by using photoluminescence(PL),time-resolved photoluminescence(TRPL),and ultrafast transient absorption(TA)measurements,the unbalance between the electron and hole in diffusion and transfer,which limits the performance of the Cs_(2)AgBiBr_(6) PSCs,was further revealed.Considering this issue,a strategy of using the mesoporous TiO_(2) electron transport layer(ETL)to construct a bulk heterojunction in Cs_(2)AgBiBr_(6) PSCs was proposed.Consequently,the PCE had improved by over 24%comparing with that only used compact TiO_(2) ETL.Moreover,based on mesoporous TiO_(2),the unencapsulated Cs_(2)AgBiBr_(6) PSCs maintained 90%of their initial performance after approximately 1200 h of storage in a desiccator(humidity~30%).This work gives further understanding of Cs_(2)AgBiBr_(6) perovskite and demonstrates that a proper design of balancing the electron and hole diffusion can improve device performance.
文摘光催化因其可以利用太阳能进行光解水产氢、CO_(2)还原、降解有机污染物及有机物转化而被认为是解决当前能源危机和环境问题的一种有效手段.由于光催化反应是由光激发光催化材料生成光生载流子引发的,因此理想的光催化剂应当具有宽的光响应范围、低的光生载流子复合率和足够的氧化还原能力来进行表面反应.然而单一组分的半导体材料难以同时满足宽光谱响应(即窄带隙)和强氧化还原能力(即价带更正和导带更负).通过耦合两个具有可见光响应且交错能带排布的半导体来构建S型异质结,不仅能拓宽光催化剂的光吸收范围、促进电荷分离,还同时保留了两种半导体的强氧化还原能力,是发展高效光催化材料的一种有效途径.Cs_(2)AgBiBr_(6)的导带和价带分别位于–0.65 V vs.NHE和1.60 V vs.NHE,而Bi_(2)WO_(6)的导带和价带分别为–0.4 V vs.NHE和2.4 V vs.NHE,两者能带位置匹配.因此,本文选择Cs_(2)AgBiBr_(6)和Bi_(2)WO_(6)用于构建S型异质结复合材料,采用超声辅助方法处理含有Cs_(2)AgBiBr_(6)量子点和Bi_(2)WO_(6)微米花的乙酸乙酯溶液,通过在Cs_(2)AgBiBr_(6)量子点和Bi_(2)WO_(6)微米花界面间形成Bi–Br键,组装出了Cs_(2)AgBiBr_(6)量子点/Bi_(2)WO_(6)微米花异质结复合材料,并考察了材料在可见光照射下还原CO_(2)的光催化活性.结果表明,所制备的Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6)异质结复合材料具有优越的光催化还原CO_(2)生成CO和CH4性能,发现在一系列含有不同比例的x Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6)异质结复合材料中(x为Cs_(2)AgBiBr_(6)与Bi_(2)WO_(6)的质量比,x=0.2,0.5,1.0),0.5 Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6)异质结复合材料表现出最优的光催化性能,在300 W氙灯(420 nm≤λ≤800 nm)照射下8 h内生成了15.4μmol g–1的CO和3.2μmol g–1的CH4.其性能明显优于同等反应条件下单纯Cs_(2)AgBiBr_(6),Bi_(2)WO_(6)以及等比例机械混合的Cs_(2)AgBiBr_(6)和Bi_(2)WO_(6)的光催化活性,这归因于Cs_(2)AgBiBr_(6)和Bi_(2)WO_(6)间形成了有效的S型异质结,该S型异质结可在不牺牲Bi_(2)WO_(6)价带空穴氧化能力和Cs_(2)AgBiBr_(6)导带电子还原能力的基础上,促进光生电子-空穴对的分离.综上,本文结果表明耦合两种具有交错能带的光催化材料来形成S型异质结是开发高效光催化剂的一种有效策略,也展示了无铅钙钛矿在光催化中的应用前景.
基金the financial support from National Natural Science Foundation of China(Grant Nos.52073164,52103088)Innovation Capability Support Program of Shaanxi(Program No.2021TD-16).
文摘In recent years, limited photocatalysis efficiency and wide band gap have hindered the application of TiO_(2) in the field of photocatalysis. A leading star in photocatalysis has been revealed as lead-free Cs_(2)AgBiBr_(6) double halide perovskite nanocrystals, owing to its strong visible light absorption and tunable band gap. In this work, this photocatalytic process was facilitated by a unique TiO_(2)/Cs_(2)AgBiBr_(6) composite, which was identified as an S-cheme heterojunction. TiO_(2)/Cs_(2)AgBiBr_(6) composite was investigated for its structure and photocatalytic behavior. The results showed that when the perovskite dosage is 40%, the photocatalytic rate of TiO_(2) could be boosted to 0.1369 min^(-1). This paper discusses and proposes the band gap matching, carrier separation, and photocatalytic mechanism of TiO_(2)/Cs_(2)AgBiBr_(6) composites, which will facilitate the generation of new ideas for improving TiO_(2)’s photocatalytic performance.
基金financially supported by the National Natural Science Foundation of China(Nos.22179053,22279046 and 21905119)the Natural Science Excellent Youth Foundation of Jiangsu Provincial(No.BK20220112)+1 种基金the Open Competition Mechanism Project of Carbon Neutrality of Jiangsu Province(No.BE2022026)Zhejiang Province Selected Funding for Postdoctoral Research Projects(No.ZJ2021001)for financial support。
文摘The valence band offset between Cs_(2)AgBiBr_(6)and hole transport layer(HTL)is approximately 1.00 e V,which results in high energy loss and is identified as one of the bottle necks of Cs_(2)Ag BiBr_(6)perovskite solar cell(PSC)for achieving high power conversion efficiency(PCE).To tackle this problem,we propose the optimization of the energy level alignment by designing and synthesizing novel deep-level hole transport materials(HTMs).The sole introduction of deep-level HTMs successfully reduces the valence band offset between Cs_(2)Ag Bi Br_(6)and HTL,but induces the increased valence band offset at HTL/Au interface,limiting the PCE improvement.To further solve the problem and improve the PCE,the gradient energy level arrangement is constructed by combining the newly developed deep-level HTM 6,6’-(3-((9,9-dimethyl-9H-fluoren-3-yl)(4-methoxyphenyl)amino)thiophene-2,5-diyl)bis(N-(9,9-dimethyl-9H-fluoren-2-yl)-N,9-bis(4-methoxyphenyl)-9H-carbazol-3-amine)(TF)with 2,2’,7,7’-tetrakis(N,N’-dipmethoxyphenylamine)-9,9-spirobifluorene(Spiro-OMeTAD).Through optimization,an impressive PCE of 3.50%with remarkably high open-circuit voltage(V_(oc))and fill factor(FF)is achieved,qualifying it among the best pristine Cs_(2)AgBiBr_(6)PSCs.
基金supported by the National Natural Science Foundation of China(51772135 and 52002148)the Ministry of Education of China(6141A02022516)+2 种基金the Fundamental Research Funds for the Central Universities(11619103)Guangdong Basic and Applied Basic Research Foundation(2020A1515011377)the support from China and Germany Postdoctoral Exchange Programthe financial support from Agency for Science,Technology,and Research(A*STAR),Singapore by the AME Individual Research Grants(A1883c0004)。
基金financially supported by the Research Fellow Scheme(RFS2021-1S04)the Theme-based Research(T42-103/16-N)of the Research Grants Council of Hong Kong SAR,ChinaFoshan Innovative and Entrepreneurial Research Team Program(2018IT100031)。
文摘无铅双钙钛矿由于具有较好的稳定性和无毒的特点吸引了很多学者的目光,有希望成为下一代光伏和光电子材料.然而,目前其光电器件性能并不理想.我们报道了一个简单的溶液法用于制备无机双钙钛矿Cs_(2)AgBiBr_(6)和MA_(2)AgBiBr_(6)微米片.与传统的溶液旋涂法相比,这种方法得到的Cs_(2)AgBiBr_(6)和MA_(2)Ag Bi Br_(6)微米片具有很好的结晶性.将它们做成光电探测器后,其响应度达到了245 mA W^(-1),比旋涂法制备的器件高出两个量级,且响应时间为145μs.热稳定性研究表明,将Cs_(2)AgBiBr_(6)器件在空气中加热到160℃再回到室温,其光电响应并没有受到影响.这些结果表明,溶液法制备无铅双钙钛矿具有更广阔的应用前景.
