Synergetic Excess PbI₂ and Reduced Pb Leakage Management Strategy for 24.28% Efficient, Stable and Eco‐Friendly Perovskite Solar Cells

Abstract

Introducing excess PbI2 has proven to be an effective in situ passivation strategy for enhancing efficiency of perovskite solar cells (PSCs). Nevertheless, the photoinstability and hysteresis are still tough issues owing to the photolysis nature of PbI2. Moreover, the humidity‐related degradation of perovskite films is also a difficult territory to cover in such an in situ passivation strategy. Herein, a synergistic strategy is reported via initiatively inducing vertical graded PbI2 distribution (GPD) in the whole perovskite film and capping a cis‐Ru(H2dcbpy)(dnbpy)(NCS)2 (Z907) internal encapsulation (IE) layer on the surface to ameliorate the above issues. The GPD design can enhance luminescence, prolong carrier lifetimes, ascertaining the improvement of efficiency and elimination of photoinstability in the PSCs. Besides, the introduced IE layer not only can promote the moisture and thermal resistance, but also inhibit Pb leakage and ion migration in the PSCs. Through the synergetic regulations, the resultant PSCs exhibit an impressive open circuit voltage (VOC) of 1.253 V, fill factor of 81.25%, and power conversion efficiency (PCE) of 24.28%. Moreover, the PSCs maintain 91% of its initial PCE at relative humidity of 85% after 500 h aging and 94% under continuous heating at 85 °C after 750 h aging.

Understanding Microstructural Development of Perovskite Crystallization for High Performance Solar Cells

“…As can be seen from the hydrogen spectrum in Figure S4b, Supporting Information, due to the interaction between CBEV and PbI 2 , the H atoms belong to ─O─C─CH═CH 2 occur chemical shift after introduction of PbI 2 , indicating the change of the surrounding chemical environment of ─O─C─CH═CH 2 group. [ 39 ] At the same time, we can seen from the carbon spectra in Figure S4c,d, Supporting Information, the C atoms belong to C═O and C═C in CBEV occur chemical shift, which are due to the coordination of C═O to Pb 2+ and the iodine anion−π interaction. [ 40 ] There is the same phenomenon for N 1s orbital (Figure S5a,b, Supporting Information).…”

Dual‐Interface Modulation with Covalent Organic Framework Enables Efficient and Durable Perovskite Solar Cells

“…The reduction of PbI 2 peak may be derived from the strong interaction between PbI 2 and HS-COFs. [49] Furthermore, to gain a thorough understanding of the interaction between HS-COFs and perovskites, X-ray photoelectron spectroscope (XPS) and the Fourier transform infrared (FTIR) spectroscopy were measured. As displayed in Figure 4g, the HS-COFs treatment leads to an ≈0.20 eV shift to higher binding energy positions in the Pb 4f spectra, indicating the interaction between HS-COFs and Pb 2+ .…”

Synergistic Defect Passivation and Crystallization Modulation in Efficient Perovskite Solar Cells: The Case of Multifunctional 2-Anisidine-4-Sulfonic Acid

“…Defects at surface and GBs not only lead to nonradiative charge recombination and ion migration but also accelerate external moisture infiltration, causing the decomposition of perovskite films. , Considering that the long-term stability is a huge obstacle to the commercial application of PSCs, the humidity stability of the perovskite films and relevant devices was also investigated. Resistance to water erosion of the perovskite films before and after 2A4SA doping exposed to the ambient atmosphere (20–30 °C and 20–60% RH) was monitored by XRD (Figure a), and the optical photographs of the perovskite films in aging on different days were tracked, as shown in Figure b.…”