Stability is a crucial factor in the commercialization of perovskite solar cells (PSCs). CsPbBr3 PSCs, despite being less efficient than organic–inorganic hybrid PSCs, have a significant advantage in terms of stability. This makes them have promising potential for commercialization. In this study, high-quality all-inorganic CsPbBr3 perovskite films were prepared by using a multistep method in ambient air conditions. The crystalline quality of the CsPbBr3 films was improved by adding an appropriate amount of ammonium acetate (NH4Ac) to the PbBr2 precursor solution. Finally, carbon-based hole transport layer-free CsPbBr3 PSCs were fabricated by selecting NH4Ac-optimized light-absorbing layers and carbon electrodes that have a good commercialization prospect. Compared with control devices, the NH4Ac-optimized CsPbBr3 cell devices significantly improved in both efficiency and stability. The photoelectric conversion efficiency increased from 7.80% to 9.68%. This study provides an effective strategy for the preparation of high-quality films by using a multistep method and is also of great significance in promoting the commercialization of PSCs.
Yao-Bing Huang,Ping-Ping Xin,Jia-Xin Li,Yue-Ying Shao,Chao-Bo Huang,Hui Pan
The dissolution of cellulose in tetrabutylammonium acetate (TBAA) and dimethyl sulfoxide (DMSO) mixed solvent was studied at room temperature (approximately 25 °C). The ratio of TBAA in the mixed solvent system (WTBAA) was found to have great influence on the solubility of cellulose and the corresponding dissolution time. The mixed solvent of WTBAA = 0.15 possessed the highest cellulose solubility and shortest dissolution time. Various cellulosic materials were well-dissolved in the solvent with a maximum solubility up to 8.17 wt %. A mechanistic study regarding the interaction between the solvent system and the model compound cellobiose was conducted using 1H NMR, 13C NMR, ATR-FTIR, conductivity, and viscosity measurements. The results implied that TBAA existed at two different states in the mixed solvent as the ratio of TBAA varied (i.e., ion-split stage (WTBAA ≤ 0.15) and ion-paired stage (WTBAA ≥ 0.15)). WTBAA = 0.15 was the turning point of these two stages, and the mixed solvent displayed the best dissolving ability at this ratio. This finding suggests that a balance between the ion concentration and ion mobility is crucial to the dissolving ability of a mixed solvent. The solvation effect of the cosolvent DMSO helped to dissociate TBAA into free ions and facilitate the ion mobility. The hydroxyl protons of cellobiose were demonstrated to form strong hydrogen bonds with CH3COO–, which was key to the dissolution of cellulose. Finally, the interaction between cellobiose and DMSO in the TBAA/DMSO/cellobiose system was investigated and was demonstrated to be another important factor for the dissolution of cellulose by stabilizing the dissolved cellulose chain from further formation of inter- and intramolecular hydrogen bonds.
Carbon-based all-inorganic perovskite solar cells (PSCs) have attracted tremendous attention due to the higher intrinsic stability, which is beneficial to lower fabrication costs and further commercial applications. Furthermore, for the purpose of promoting the industrialization of PSCs, it is crucial to explore preparation methods in ambient air condition. Herein, ammonium acetate (NH 4 Ac) is added into the antisolvent for the first time in carbon-based all-inorganic PSCs under the full ambient air condition. It could improve the quality of perovskite films by adjusting the nucleation density and utilizing intermediate phase to retard crystallization. By regulating the concentrations of NH 4 Ac, the perovskite films with dense and pinhole-free, large grain size, few grain boundaries and less defects are finally formed. Ultimately, the optimal device achieved a high efficiency of 15.43%, which is a new record value for carbon-based all-inorganic PSCs.
Carbon-based all-inorganic perovskite solar cells are currently emerging as a commercial and promising photovoltaic device . Rutile TiO 2 has the function of UV shielding and preventing the decomposition of perovskite, furthermore, TiO 2 nanorod array provides the direct 1-D electron transmission channel. Herein, vertically oriented rutile TiO 2 nanorods array are synthesized on the FTO substrate by a simple one-step hydrothermal process and used as the electron transfer layer. The analysis of characterization illustrates that the prepared TiO 2 is a flawless single rutile phase. TiO 2 nanorods are employed as an ETL to provide a passage for the rapid and direct charge transfer. The separation of electrons and holes can be enhanced by ammonium acetate treatment of the TiO 2 nanorod ETL/perovskite interface, and the carrier recombination can be efficiently lowered. Based on the structure of FTO/TiO 2 @CH 3 COONH 4 /CsPbI 2.25 Br 0.75 /C, the best device containing 2.5 mg/mL ammonium acetate modified TiO 2 nanorods showed a short-circuit current density of 14.55 mA/cm 2 , open-circuit voltage of 1.08 V, and fill factor of 69.45 %, yielding a power conversion efficiency of 11.53 %, which show an increase in efficiency of approximately 22.4% when compared with the control cell. The results show that ammonium acetate interface modification is an effective strategy to enhance the photovoltaic performance of PSCs.
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