Wei-Kang Xu,Feng-Xiang Chen,Gong-Hui Cao,Jia-Qi Wang,Li-Sheng Wang
To date, many efforts have been made to improve the performance of paintable carbon-based (PC-based) perovskite solar cells (PSCs). Though great progress has been achieved, their power conversion efficiencies are still relatively low compared with hole-transport-materials-based PSCs. General research on influencing factors of performance in PC-based PSCs is still insufficient. In this work, PC-based PSCs were fabricated in ambient air and four groups of controlled experiments were performed in which the PbI2 layers were prepared with or without antisolvent extraction treatment. These four groups of experiments were designed to find out the effect of different influencing factors on PC-based PSCs performance, for example, PbI2 residual, the surface morphology of the perovskite film, the surface roughness of the perovskite film, and the contact status of the perovskite/carbon electrode interface. With a systematic analysis, we demonstrated that the contact status of the perovskite/carbon electrode interface played a vital role in PC-based PSCs, and a flat, smooth perovskite surface could help to improve this contact status significantly. Besides, on the precondition of a poor contact interface, no PbI2 residual and a good surface morphology only brought limited benefits to the performances of PC-based PSCs.
Li Xiao,Jia Xu,Jing Chen,Jicheng Luan,Yi Yang,Bing Zhang,Jianxi Yao,Songyuan Dai
The remnant PbI2 at the mesoporous-TiO2 (m-TiO2)/CH3NH3PbI3 interface can act as an interface modification layer for high-efficiency perovskite solar cells (PSCs). In this study, we adopted Pb(CH3COO)2·3H2O (PbAc2) to control the amount of remnant PbI2 at the m-TiO2/CH3NH3PbI3 interface. The characterization results demonstrate that the amount of remnant PbI2 could be controlled by the concentration of PbAc2 solution without influencing the crystallographic textures of CH3NH3PbI3 films. By adjusting the PbAc2 solution concentration, the optimized PSC can achieve a 15% enhancement of PCE in the case of using a two-step method for CH3NH3PbI3 preparation. Under the circumstances of using an anti-solution method, it still displayed a 10% enhancement of the average PCE for 10 individual PSCs with PbAc2 (13.6% to 15.0%). The steady-state photoluminescence (PL), time-resolved photoluminescence (TR-PL) and open-circuit voltage decay results demonstrated that the remnant PbI2 could reduce carrier recombination at the m-TiO2/CH3NH3PbI3 interface. Meanwhile, the enhancement of the open-circuit voltage was achieved for PSCs with PbAc2.
All-inorganic perovskite solar cells require high-temperature preparation processes, which severely hinders their further commercial development. Inorganic perovskite materials have a high crystallization barrier, so the crystallinity is poor under low temperature conditions, resulting in poor device performance. Therefore, it is an important challenge to develop an excellent low-temperature preparation process. In this paper, the crystallization kinetics of the CsPbI 2 Br perovskite film under low temperature conditions was studied, and it was found that the perovskite was not completely crystallized during low temperature crystallization , and PbI 2 remained. The PbI 2 residue not only caused the appearance of lead defects but also formed insoluble CsBr due to the insufficient reaction of the raw materials. Through the interaction between the organic molecules 3-Amino-3-(3-pyridyl)propionic Acid (PA) and PbI 2 , the crystallization reaction process can be effectively improved. Eliminating the residual PbI 2 also effectively inhibited the precipitation of CsBr, thereby significantly improved the crystallinity of CsPbI 2 Br. Efficiencies of 10.95% are achieved for low-temperature-processed CsPbI 2 Br planar-architecture FTO/SnO 2 /CsPbI 2 Br/carbon, and the obtained device also showed good stability in the air.
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