Dithiol surface treatment towards improved charge transfer dynamic and reduced lead leakage in lead halide perovskite solar cells

Abstract

With efficiency surpassing 25%, perovskite solar cells (PSCs) have received much attention because of their excellent potential in photovoltaic field. However, there are some challenging issues still exist which need to be addressed.One issue is that the surface/interface and grain boundaries related defects and traps could work as charge recombination centers during the device operation, compromising the charge transfer as well as the device performance. Another issue is the leakage of toxic Pb, which may cause undesired contamination to water or soil and make devices not appropriate to work outdoors. Herein, the dithiol molecule was introduced to passivate surface defects and traps as well as reduce the Pb leakage. The unsaturated Pb 2+ usually acting as recombination centers could coordinate with thiol group to reduce the recombination. Meanwhile, the beneficial band bend was observed, which facilitates the interface charge transfer. Crucially, we confirmed dithiol molecule could help reduce the Pb leakage. Retarded dissolution of PbI 2 into water was observed for perovskite films after dithiol treatment, which eventually contributed less Pb leakage. Overall, this study proposes a universal strategy for defects passivation and reduced lead leakage, which is promising for environmental stable optoelectronic applications.

An Interface Co-modification Strategy for Improving the Efficiency and Stability of CsPbI3 Perovskite Solar Cells

“…Furthermore, the energy level alignment of PSCs must have been changed after PCBM&2FPPD co-modification, so valence band X-ray photoelectron spectroscopy (VB XPS) and ultraviolet photoelectron spectroscopy (UPS) were deployed for characterization (Figure S7), which can reveal the energy level shift of the film surface . The VB XPS spectra (Figure S7a) show that the VB energy of PVK/2FPPD is reduced, indicating that the semiconductor type of PVK/2FPPD shifts to p-type and there exists deeper band bending, which can help to reduce the energy barrier between PVK and HTL. , Meanwhile, UPS was used to characterize the energy level alignment of PSCs (Figure S7b–d). The work function ( WF ) can be calculated by the cut-off energy ( E cutoff ) region (Figure S7c) according to following formula: WF = 21.22 – E cutoff (eV), where 21.22 eV is the energy of ultraviolet photoelectrons.…”

Mitigating Potential Lead Leakage Risk of Perovskite Solar Cells by Device Architecture Engineering from Exterior to Interior

“…As a result, Pb leakage can be significantly mitigated. 136 Chen et al introduced the chemically stable Dion-Jacobson 2D perovskite material of (DOE)PbI 4−x Cl x (DOE 2+ : 2,2′-dithiobis(ethylamine) cations) at the 3D perovskite surface, and the Pb leakage was significantly slowed down. 137 Mesoporous Lead-Adsorption Scaffold.…”

“…Similarly, Wang et al introduced an effective method by using 1,2-ethandeithiol (1,2-EDT) to molecularly modulate the surface of perovskite. As a result, Pb leakage can be significantly mitigated . Chen et al introduced the chemically stable Dion-Jacobson 2D perovskite material of (DOE)­PbI 4– x Cl x (DOE 2+ : 2,2′-dithiobis­(ethylamine) cations) at the 3D perovskite surface, and the Pb leakage was significantly slowed down …”

Ecotoxicity and Sustainability of Emerging Pb‐Based Photovoltaics

“…(Figure 14f ) Wang et al introduced the dithiol molecule to passivate surface defects and trap Pb ions. [128] Consequently, Pb content from the 1,2-ethandeithiol (1,2-EDT) treated perovskite films was reduced than pristine perovskite films when immersed in DI water and was monitored and recorded as shown in Figure 14g. Chen et al introduced a chemically stable Dion-Jacobson 2D perovskite of (DOE)PbI 4Àx Cl x at the 3D perovskite surface.…”