Triphenylamine–Polystyrene Blends for Perovskite Solar Cells with Simultaneous Energy Loss Suppression and Stability Improvement

Abstract

Energy loss induced by nonradiative recombinations plays a critical role in determining power conversion efficiencies in perovskite solar cells, whereas device stability impacts their long‐time reliability in the ambient environment. It is an important challenge to suppress energy loss and improve device stability simultaneously. Herein, an interfacial layer of triphenylamine (TPA):polystyrene (PS) blend coated on the hybrid perovskite layer to concurrently suppress energy loss and improve device stability is reported. The energy loss is suppressed from 0.49 to 0.35 eV by passivating surface defects in hybrid perovskites via Lewis acid–base interactions with the combination of electron‐donating aromatic nucleus in PS and tertiary amine in TPA, leading to perovskite solar cells with a high open‐circuit voltage of 1.18 V, a fill factor of about 80%, and a power conversion efficiency of 22.1%. Meanwhile, the device stability in the ambient environment is improved significantly by the TPA:PS blend due to its superior hydrophobicity which is suggested by its high contact angle of 91.1° as compared to 64.0° for the pristine perovskite film. Herein, an efficient interfacial engineering approach with the TPA:PS blend to suppress energy loss and improve device stability simultaneously towards realistic applications is demonstrated.

Grain Boundary Defects Passivated with tert-Butyl Methacrylate for High-Efficiency Perovskite Solar Cells

“…The typical (001) peak of 12.7° is assigned to the hexagonal PbI 2 phase, originating from the excessive PbI 2 in the perovskite film, as shown in Figure c, being consistent with the excess PbI 2 contained in the precursor solution . The characteristic peaks at 14.1 and 24.4° belong to the (110) and (111) planes of the tetragonal perovskite phase, respectively . Notably, there is no obvious shift in the perovskite diffraction angle, indicating that TBA cannot be embedded into a crystal lattice and can only accumulate ultimately at GBs .…”

“…37 The characteristic peaks at 14.1 and 24.4°belong to the (110) and (111) planes of the tetragonal perovskite phase, respectively. 38 Notably, there is no obvious shift in the perovskite diffraction angle, indicating that TBA cannot be embedded into a crystal lattice and can only accumulate ultimately at GBs. 39 It is found that the ratio of the (001) peak to the main peak (111) in the perovskite film decreases obviously, from 1.49 for the pristine perovskite to 0.95 for the TBA−perovskite sample, indicating that more PbI 2 precursors are transformed into the perovskite phase.…”

“…The roughness ( R q ) of the TBA–perovskite film is 21.90 nm, smaller than 27.90 nm of the control sample. A smoother perovskite surface will be beneficial to the deposition of the hole transporting layer and improve the interfacial contacts, resulting in lower series resistance and higher FF . Moreover, there are fewer grain boundaries in the TBA–perovskite layer where the photogenerated charge carriers accumulate, promoting the charge transport in the perovskite film.…”

The evolution of triphenylamine hole transport materials for efficient perovskite solar cells

“…Interestingly, this device maintained 91% of its maximum efficiency for 10 days after storage under ambient conditions, which includes a relative humidity of 40-60%. 146 Recently, the p-type doped conducting polymer 9,9-dioctylfluorene-co-bis-N,N-((-4-butyl phenyl)-bis-N,N-phenyl-1,4-phenylenediamine) (PFB) was successfully employed as an HTM in PSCs. The highest PCE obtained for the fabricated n-i-p mesoscopic PSCs was 14.04%, which is 57% higher than that of the pristine PFB HTL.…”

“…Interestingly, this device maintained 91% of its maximum efficiency for 10 days after storage under ambient conditions, which includes a relative humidity of 40–60%. 146…”