Functionalization of Donor–π–Acceptor Hole Transport Materials Enhances Crystallization and Defect Passivation in Inverted Perovskite Solar Cells: Achieving Power Conversion Efficiency >21% (Area: 1.96 cm²) and Impressive Stability

Abstract

Inverted perovskite solar cells (PSCs) mainly adopt polytriarylamine (PTAA) for the hole transport material (HTM), which usually brings about inferior interfacial contact owing to their hydrophobicity, high‐lying highest occupied molecular orbital energy level, and deficiency of passivation groups. Herein, a series of donor–π–acceptor (D–π–A) type small molecules is demonstrated based on 2,2′:6′,2″‐terpyridine (TPy) as the acceptor moiety, benzene ring as the π‐linker, and incorporating various donors to act as HTMs. These TPy‐based molecules coated atop PTAA manipulate the energy level and surface wettability, but the incorporation of the phenoxazine (POZ) donor can be prominent for enhancing charge transport and defect passivation, thereby simultaneously addressing the above‐mentioned issues. The highest power conversion efficiency of 22.36% can be achieved with an open‐circuit voltage (VOC) of 1.15 V, a short‐circuit current density (JSC) of 23.96 mA cm−2, and a fill factor (FF) of 81.16% for the optimized POZ‐TPy‐modified device. Moreover, the power PCE of a large POZ‐TPy‐modified device (1.96 cm2) can still reach more than 21%. These results are among one of the highest efficiencies for inverted PSCs, indicating the enormous potential of POZ‐TPy HTM in future perovskite applications.

Exploring the Charge-Transport and Optical Characteristics of Organic Doublet Radicals: A Theoretical and Experimental Study with Photovoltaic Applications

“…As illustrated in Figure S15(b), a slightly narrower fwhm can be observed for the normalized signal of perovskite film grown on radical 2 , implying the formation of better crystal orientations. The higher quality of perovskite is derived from the suitable surface energy, leading the mitigation of the interfacial defects, which is in line with the SEM results.…”

“…Nevertheless, defects frequently appear at the interface between the CTL and the perovskite layer, leading to nonradiative recombination of charge carriers and reduced device efficiency. To address this issue, many researchers have attempted to passivate these defects by introducing a buried layer or interlayer between the CTL and the perovskite layer. − Various radicals have been developed as perovskite additives, including TEMPO, DMBI-2-Th-I, and TTM . These radicals have demonstrated varying levels of effectiveness in passivating PSCs, minimizing trap density, and reducing recombination within the devices.…”

Enhancement of Efficiency of Perovskite Solar Cells with Hole-Selective Layers of Rationally Designed Thiazolo[5,4-d]thiazole Derivatives

“…As shown in Figure S15a, the diffraction angles (2θ) of 14.1, 20.1, 24.6, and 28.5° correspond to the (1 0 0), (1 1 0), (1 1 1), and (2 0 0) crystal planes of the perovskite, respectively. , The distinctive diffraction peak at 12.7° represents residual PbI 2 . However, in the TTP-DPA- contacting perovskite film, there is no evident diffraction peak at 12.7°, indicating that the TTP-DPA surface fosters perovskite growth, possibly due to its appropriate surface energy in suppressing perovskite grain boundary defects …”

“…However, in the TTP-DPA- contacting perovskite film, there is no evident diffraction peak at 12.7°, indicating that the TTP-DPA surface fosters perovskite growth, possibly due to its appropriate surface energy in suppressing perovskite grain boundary defects. 60 …”

“…However, in the TTP-DPA-contacting perovskite film, there is no evident diffraction peak at 12.7°, indicating that the TTP-DPA surface fosters perovskite growth, possibly due to its appropriate surface energy in suppressing perovskite grain boundary defects. 60 We conducted PL measurements using the sample structure of ITO/HSL/perovskite to investigate the influence of compound TTP-DPA on the optoelectronic properties. As illustrated in Figure S15b, the trend of PL intensity is 2PACz/ TTP-DPA > 2PACz > TTP-DPA.…”