A Solution Processable D-A-D Molecule based on Thiazolothiazole for High Performance Organic Solar Cells
A Solution Processable D-A-D Molecule based on Thiazolothiazole for High Performance Organic Solar Cells
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DOI：
10.1002/aenm.201100505
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发表时间：
2012-01-01
影响因子：
27.8
通讯作者：
Zhan, Xiaowei
中科院分区：
文献类型：
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作者：
Shi, Qinqin;Cheng, Pei;Zhan, Xiaowei
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA，魏因海姆高级能源材料。2012，2，63-67中所述的装置的吸收率高于基于PC 61 BM的装置的吸收率（1.85%），这可能是由于PC 71 BM相对于PC 61 BM具有更好的吸收。在110 ℃下热退火10分钟，Jsc和FF分别提高到9.39 mA cm− 2和43.7%。改进的Jsc和FF导致效率提高3.73%，相对于铸态装置的效率提高44%（表1，图2a）。制作了20多个器件，它们的平均PCE为3.61%。图2b中示出了在110 ℃退火和不退火的情况下，供体/受体重量比为1：4的共混物薄膜的入射光子转换电流效率（IPCE）和吸收光谱。与纯TT-TTPA固体膜相比，共混物的吸收增宽并延伸到700 nm，这是由于PC 71 BM的贡献。还观察到退火后共混物膜的吸光度增加。TT-TTPA：PC 71 BM（1：4，w/w）的共混物在300和700 nm之间表现出宽的IPCE平台，在480 nm处最大为49%。PC 71 BM对IPCE有显著贡献，与PCE数据一致。热退火使IPCE最大值提高到55%。为了了解载流子输运对光伏性能的影响，我们采用空间电荷限制电流（SCLC）方法测量了共混物中的空穴和电子迁移率。图3示出了仅空穴（a）和仅电子（B）器件的J-V曲线，所述器件在铸造时加工并在110 ℃下退火。共混物铸态的平均空穴和电子迁移率分别为3.66× 10− 7 cm 2 V− 1 s− 1和1.03× 10− 4 cm 2 V− 1 s− 1。在低施主浓度（20%）下，空穴传输的逾渗路径形成不良，导致较低的空穴迁移率;而在高受主浓度（80%）下，电子传输的逾渗路径形成良好，导致较高的电子迁移率。在110 C退火10 min后，共混物显示出1.28× 10− 6 cm 2 V− 1 s− 1的空穴迁移率和3.02× 10− 6 cm 2 V− 1 s− 1的电子迁移率。纯TT-TTPA薄膜的X射线衍射（XRD）图谱（支持信息中的图S2）
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Adv. Energy Mater. 2012, 2, 63–67 devices is higher than that (1.85%) of the PC61BM-based devices, probably due to better absorption of PC71BM relative to PC61BM. Thermal annealing at 110 C for 10 min improves Jsc and FF to 9.39 mA cm− 2 and 43.7%, respectively. The improved Jsc and FF leads to an enhanced efficiency of 3.73%, 44% enhancement relative to that for the as-cast device (Table 1, Figure 2a). More than 20 devices were fabricated and their average PCEs were 3.61%. The incident photon to converted current efficiency (IPCE) and absorption spectra of the blend thin film with donor/acceptor weight ratio of 1: 4 without and with annealing at 110 C are shown in Figure 2b. Compared to that of pure TT-TTPA solid film, absorption of the blend broadens and extends to 700 nm as a result of contribution from PC71BM. Increase in the absorbance of the blend film after annealing was also observed. The blend of TT-TTPA: PC71BM (1: 4, w/w) exhibits a broad IPCE plateau between 300 and 700 nm with a maximum of 49% at 480 nm. PC71BM makes significant contribution to IPCE, which is consistent with the PCE data. Thermal annealing improves the IPCE maximum to 55%.To understand the influence of charge carrier transport on photovotaic performance, we used space-charge limited current (SCLC) method to measure the hole and electron mobilities in the blend. Figure 3 shows the J–V curves for hole-only (a) and electron-only (b) devices processed as cast and annealed at 110 C. The average hole and electron mobilities for the blend as-cast were found to be 3.66× 10− 7 cm2 V− 1 s− 1 and 1.03× 10− 4 cm2 V− 1 s− 1, respectively. The percolation pathways for hole transport are poorly formed at low donor concentration (20%), leading to lower hole mobilities; while the percolation pathways for electron transport are well formed at high acceptor concentration (80%), leading to higher electron mobilities. After annealing at 110 C for 10 min, the blend exhibited hole mobility of 1.28× 10− 6 cm2 V− 1 s− 1 and electron mobility of 3.02× 10− 6 cm2 V− 1 s− 1. The X-ray diffraction (XRD) patterns of pure TT-TTPA thin films (Figure S2 in Supporting Information)