Halide perovskite solar cells (PSCs) have attracted widespread attention due to their low cost and excellent optoelectronic properties. To improve efficiency and stability, two-dimensional/three-dimensional (2D/3D) halide perovskite heterostructures are widely used in PSCs. However, interfacial defects between the 2D and 3D perovskites and uneven coverage of the 2D overlayer limit the long-term stability and uniform charge extraction of PSCs.
To address these issues, the research team led by Professors Qiu Longbin and Qi Yabing proposed a strategy for surface planarization on 3D perovskite surfaces. This strategy enables the epitaxial growth of uniform 2D/3D perovskite heterostructures via a vapor-assisted process. Using a mixed solvent of isopropyl alcohol (IPA) and dimethyl sulfoxide (DMSO) as a planarizing agent, they restructured the 3D perovskite surface to form a uniform 2D overlayer. On the planarized 3D perovskite surface, PbI₂ was deposited via a vapor-assisted process to form a uniform 2D/3D perovskite heterostructure. By forming a uniform 2D/3D interface, uniform charge extraction and suppression of interfacial non-radiative recombination are achieved.
The surface planarization strategy significantly improves the uniformity and stability of the 2D/3D perovskite heterostructure, achieving a stable power output efficiency of 25.97%. The encapsulated PSMs maintained an efficiency of 96.9% after 1246 hours of continuous illumination at 65°C; under the ISOS-O-1 protocol, the efficiency remained at 91.1% after 862 hours.
This study demonstrates a method for fabricating uniform 2D/3D perovskite heterostructures through a surface planarization strategy, significantly improving the efficiency and stability of PSCs. The planarization strategy achieved a high efficiency of 26.02%, and 23.06% in PSMs with an active area of 22.8 cm². Furthermore, the encapsulated PSMs exhibited excellent stability and durability under long-term operating conditions, paving the way for the commercialization of large-scale perovskite photovoltaic technology.
Figure 1. Scheme and effect of planarized 3D perovskites. a) Illustration of the benefits of planarized 2D/3D perovskites heterojunction. The surface planarization of 3D perovskites helps form a uniform 2D capping layer and reduce interfacial defects, which can slow down the outward diffusion of the components from perovskite, suppress interfacial nonradiative recombination, and improve the homogeneity of charge extraction. b) Illustration of the surface planarization. The DMSO@IPA can planarize the surface of 3D perovskite. c) Illustration of the growth model of PbI2 deposited on planarized and control 3D perovskites. The planarized 3D perovskite, with a higher surface energy and better lattice matching with PbI2, can form a uniform PbI2 layer. In contrast, the vapor-deposited PbI2 on the surface of the control 3D perovskite is discontinuous. d,e) AFM-IR images of (d) control 3D perovskite and (e) planarized 3D perovskite. f) The surface energy of control and planarized 3D perovskites.
Figure 2. Epitaxy vapor-assisted growth of uniform 2D/3D perovskites. Top surface SEM images of (a) control 3D perovskite with vapor-deposited PbI2 and (b) control 2D/3D perovskite. c) A cross-sectional SEM image of the planarized 2D/3D perovskite. Top surface SEM images of (d) planarized 3D perovskite with vapor-deposited PbI2 and (e) planarized 2D/3D perovskite. f) A cross-sectional SEM image of the planarized 2D/3D perovskite.patterns of (g) the control 2D/3D and (h) the planarized 2D/3D perovskite films. i) Radial intensity profiles averaged over the entire 2D GIWAXS image.
Figure 3. Carrier transport performance of planarization-epitaxial growth uniform 2D/3D perovskite heterojunction. UPS spectra: a) the secondary electron onset region and b) the valence band region for control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D perovskite films. c) Schematic of energy diagram for the control 2D/3D and planarized 2D/3D perovskite. The orange lines denote the surface trap state in control 3D perovskite, and the black arrows denote the nonradiative recombination pathways and the directions of carrier drift. The interface between control 3D and 2D forms a type-I band alignment, whereas the interface between planarized 3D and 2D forms a type-II band alignment. d) Steady-state PL spectra and (e) TRPL decay curves of control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D perovskite films deposited on glass substrates. f) XRD patterns of control 2D/3D and planarized 2D/3D perovskites before and after aging at 100 °C for 120 min
Figure 4. Performance of the PSCs based on the perovskites with a uniform 2D/3D heterojunction by the planarization-epitaxial growth strategy. a)J–V curves of the champion control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D p-i-n PSCs with a bandgap of 1.57 eV. b) J–V curves of the champion planarized 2D/3D p-i-n PSCs with a bandgap of 1.55 eV. c) The stabilized power outputs of the champion planarized 2D/3D PSCs. d)VOC versus light intensity curves of the control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D p-i-n PSCs. e) Nyquist plots of the control 3D, planarized 3D, control 2D/3D and planarized 2D/3D p-i-n PSCs. f) EQEEL versus voltage of the control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D p-i-n PSCs. g) Stability of encapsulated PSCs under ISOS-L-1 protocol (1-sun illumination using LEDs source, ambient condition with RH of 70%). The initial PCEs of the devices based on control 3D, planarized 3D, control 2D/3D and planarized 2D/3D are 22.07%, 22.89%, 23.52%, and 24.57%, respectively. h) Stability of encapsulated PSCs under ISOS-D-3 protocol.
Figure 5. Homogeneous charge extraction in planarized 2D/3D PSMs. a) Optical photo of the planarized 2D/3D PSM. b,c) The photocurrent images of (b) control 2D/3D and (c) planarized 2D/3D PSM. d) J–V curves of the champion control 2D/3D and planarized 2D/3D PSMs with seven subcells connected in series. e) The stabilized power output of the champion planarized 2D/3D PSM. f) PCEAa distribution of the control 2D/3D and planarized 2D/3D PSMs. g) Stability of encapsulated planarized 2D/3D PSM under ISOS-L-3 protocol (1-sun illumination using LEDs source at 65 °C with RH of 70%). The initial PCEAa of planarized 2D/3D PSM is 22.53%. (h) Stability of encapsulated planarized 2D/3D PSM under ISOS-O-1 protocol (The solar module is stored outdoors, and its PCEAa was acquired using a solar simulator every two weeks).
本文来源：DOI: 10.1002/advs.202407380
https://doi.org/10.1002/advs.202407380