Yan Weibo, Yang Wensheng, Zhang Kangjie, Yu Hui, Yang Yuntian, Fan Hao, Qi Yuanyuan, Xin Hao
Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China.
ACS Omega. 2022 Sep 2;7(36):32383-32392. doi: 10.1021/acsomega.2c03802. eCollection 2022 Sep 13.
Organic Lewis bases [2,2'-bipyridine (BPY), 4-hydroxy-1,5-naphthyridine-3-carbonitrile (DQCN), and thenoyltrifluoroacetone (TTFA)] with bi-coordination sites of N and O were employed as perovskite surface defect passivants to address the efficiency and stability issues of perovskite solar cells (PSCs), with typical phenethylammonium iodide (PEAI) and piperazinium iodide (PI) passivants as reference. The surface properties of the perovskite films before and after passivation were characterized by Fourier-transform infrared, ultraviolet-visible, photoluminescence (PL), and time-resolved PL spectroscopy, X-ray diffraction, ultraviolet photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The characterizations reveal that BPY, DQCN, or TTFA forms coordination bonds with exposed "Pb", leading to a slight decrease in the highest occupied molecular orbital or lowest unoccupied molecular orbital energy level and bandgap. These passivants (especially TTFA) can passivate the perovskite surface defects to inhibit non-radiative recombination while having almost no influence on the grain size and surface morphology. Utilizing the passivated perovskite as the light absorption layer, solar cells with an inverted configuration of indium tin oxide/NiO /passivated MAPbCl I /C/BCP/Ag have been fabricated, and power conversion efficiencies of 19.22, 17.85, 16.49, 16.31, and 17.88% have been achieved from PEAI, PI, BPY, DQCN, and TTFA, respectively. All the device performance based on passivated perovskite is superior to that of the control (15.75%) owing to the reduced carrier recombination. The device from TTFA exhibits almost comparable efficiency to that of PEAI and PI controls, indicating that TTFA has an equal excellent passivation effect to state-of-the-art PEAI and PI. Furthermore, the devices based on BPY, DQCN, and TTFA show superior long-term stability with an efficiency loss of only 13.2, 16.7, and 12.9%, respectively, after being stored for 40 days in a ∼12% humidity, low-oxygen level environment, which is 45.4, 38.8, and 44.4% for the control, PEAI, and PI devices, respectively, primarily due to the improved hydrophobicity of the perovskite surface. Our results demonstrate that it is feasible to achieve high-efficiency and long-term-stable perovskite solar cells via selecting the appropriate molecules to passivate perovskite surface defects.
具有N和O双配位位点的有机路易斯碱[2,2'-联吡啶(BPY)、4-羟基-1,5-萘啶-3-腈(DQCN)和噻吩甲酰三氟丙酮(TTFA)]被用作钙钛矿表面缺陷钝化剂,以解决钙钛矿太阳能电池(PSC)的效率和稳定性问题,以典型的苯乙铵碘化物(PEAI)和哌嗪碘化物(PI)钝化剂作为参考。通过傅里叶变换红外光谱、紫外可见光谱、光致发光(PL)和时间分辨PL光谱、X射线衍射、紫外光电子能谱、扫描电子显微镜和原子力显微镜对钝化前后钙钛矿薄膜的表面性质进行了表征。表征结果表明,BPY、DQCN或TTFA与暴露的“Pb”形成配位键,导致最高占据分子轨道或最低未占据分子轨道能级和带隙略有降低。这些钝化剂(尤其是TTFA)可以钝化钙钛矿表面缺陷以抑制非辐射复合,同时对晶粒尺寸和表面形貌几乎没有影响。利用钝化后的钙钛矿作为光吸收层,制备了具有氧化铟锡/NiO /钝化的MAPbClI /C/BCP/Ag倒置结构的太阳能电池,PEAI、PI、BPY、DQCN和TTFA的功率转换效率分别达到了19.22%、17.85%、16.49%、16.31%和17.88%。由于载流子复合减少,所有基于钝化钙钛矿的器件性能均优于对照组(15.75%)。TTFA器件的效率与PEAI和PI对照组几乎相当,表明TTFA具有与最先进的PEAI和PI同等优异的钝化效果。此外,基于BPY、DQCN和TTFA的器件表现出优异的长期稳定性,在湿度约为12%、低氧水平的环境中储存40天后,效率损失分别仅为13.2%、16.7%和12.9%,而对照组、PEAI和PI器件的效率损失分别为45.4%、38.8%和44.4%,这主要是由于钙钛矿表面疏水性的提高。我们的结果表明,通过选择合适的分子钝化钙钛矿表面缺陷来实现高效和长期稳定的钙钛矿太阳能电池是可行的。