NaHCO₃‐induced porous PbI₂ enabling efficient and stable perovskite solar cells

Abstract

Driven by their many unique features, perovskite solar cells (PSCs) have become one of the most promising candidates in the photovoltaic field. Twostep preparation of perovskite film is advantageous for its higher stability and reproducibility compared to the one-step method, which is more suitable for practical application. However, the incomplete conversion of the dense lead iodide (PbI 2 ) layer during the sequential spin-coating of formamidinium/ methylammonium (FA + /MA + ) organic amine salts severely affect the performance of PSCs. Herein, sodium bicarbonate (NaHCO 3 ) is used to induce the formation of porous PbI 2 , which facilitates the penetration of the FA + /MA + ions and the formation of a perovskite film with high crystallinity and large grain microstructure. Meanwhile, the introduction of Na + not only improves the energetic alignment of the PSC, but also increases the conductivity via pdoping. As a result, the optimized NaHCO 3 -modified PSC achieves a champion power conversion efficiency of 24.0% with suppressed hysteresis. Moreover, the significant reduction in defect density and ion migration as well as a mild alkaline environment enhance the stability of device. The unencapsulated NaHCO 3 -modified PSCs maintain over 90% of their original efficiency upon storage in ambient air (30%-40% relative humidity) for 2160 h. We have demonstrated an ingenious strategy for controlling the quality of perovskite and improving the performance of device by low-temperature foaming of simple inorganic molecules of NaHCO 3 .lead iodide (PbI 2 ), perovskite solar cell, porous materials, sodium bicarbonate (NaHCO 3 ), two-step deposition Yitian Du and Ying Wang contributed equally to this study.

Synergistic Effect of 2-(Trifluoromethyl) Benzimidazole on the Stability and Performance of Perovskite Solar Cells

“…The upward shift of the E F indicates that the TFMBI-modified perovskite film exhibits more n-type properties, which is a result of the passivation of hole traps at the interface . Combining the previously E g , E cut‑off , the valence band maximum ( V BM ) and conduction band minimum ( C BM ) of the perovskite film were determined. , …”

“…34 Combining the previously E g , E cut-off , the valence band maximum (V BM ) and conduction band minimum (C BM ) of the perovskite film were determined. 35,36 Figure 4f presents the energy level distribution of the functional layers in the PSCs. The optimized gradient distribution of the functional layers is observed to be more compatible, which is conducive to the transportation and extraction of carriers, thereby enhancing the photovoltaic performance of the device.…”

Synergistic Surface Defect Passivation of Ionic Liquids for Efficient and Stable MAPbI3-Based Inverted Perovskite Solar Cells

“…Between the perovskite film and transport layers or between the transport layer and electrode, an appropriate modification layer can be added to significantly lower the number of defects in the device and increase device performance. , Passivation molecules function as electron acceptors or donors to eliminate various defects by coordinating with the charged defects in the perovskite active layer. Different passivation molecules have been reported, such as fullerenes and their derivatives, , polymers, , and organic/inorganic salts. , Because organic and inorganic salts contain ionic groups, they can simultaneously passivate positively and negatively charged defects and, thus, have been widely studied and applied. For example, Isikgor et al added phenformin hydrochloride (PhenHCl) to the surface of perovskite thin film and precursor liquid to reduce defect density of the device ( N t ) and prolong the carrier lifetime, which improved both the device performance and stability .…”

“…Different passivation molecules have been reported, such as fullerenes and their derivatives, 30,31 polymers, 32,33 and organic/inorganic salts. 34,35 Because organic and inorganic salts contain ionic groups, they can simultaneously passivate positively and negatively charged defects and, thus, have been widely studied and applied. For example, Isikgor et al added phenformin hydrochloride (PhenHCl) to the surface of perovskite thin film and precursor liquid to reduce defect density of the device (N t ) and prolong the carrier lifetime, which improved both the device performance and stability.…”

Inorganic Framework Composition Engineering for Scalable Fabrication of Perovskite/Silicon Tandem Solar Cells

“…The combination of the higher crystallinity of PbI 2 and looser arrangement of crystals in the framework collectively enhances inorganic substance conversion and perovskite film quality. 33,40 To evaluate the extent of transformation at different stages, XRD and SEM measurements of the perovskite films were performed. The light curves in XRD patterns were obtained after blade-coating organic solution without post annealing.…”