Nicotinamide as Additive for Microcrystalline and Defect Passivated Perovskite Solar Cells with 21.7% Efficiency

Abstract

Passivation of electronic defects on the surface and at grain boundaries (GBs) of perovskite films has become one of the most effective tactics to suppress charge recombination in perovskite solar cells. It is demonstrated that trap states can be effectively passivated by Lewis acid or base functional groups. In this work, nicotinamide (NTM, commonly known as vitamin B3 or vitamin PP) serving as a Lewis base additive is introduced into the PbI2 and/or FAI: MABr: MACl precursor solution to obtain NTM modified perovskite films. It has been found that the NTM in the perovskite film can well passivate surface and GBs defects, control the film morphology and enhance the crystallinity via its interaction with a lone pair of electrons in nitrogen. In the presence of the NTM additive, we obtained enlarged perovskite crystal grain about 3.6 μm and a champion planar perovskite solar cell with efficiency of 21.72% and negligible hysteresis. Our findings provide an effective route for crystal growth and defect passivation to bring further increases on both efficiency and stability of perovskite solar cells.

5‐Chloroindole as Interface Modifier to Improve the Efficiency and Stability of Planar Perovskite Solar Cells

“…The results show that the hydrogen bond (N-H…I) formed by indole or Cl-indole and iodine in the perovskite material greatly affects the N-H stretching frequency and can improve the interface contact, thereby reducing the contact resistance between the ETL and the perovskite LAL. [30,35] The photoelectrochemical characterization technique was used to investigate the interface charge carrier transportation kinetics to reveal the influence of Cl-indole modification. First, the steady-state photoluminescence (PL) spectra of the perovskite layer growth on SnO 2 without and with modification are shown in Figure 3a.…”

“…The work functions (E F ) of SnO 2 , SnO 2 /indole, and SnO 2 /Cl-indole films are calculated using formulas to be 2.28, 2.78, and 3.57 eV, respectively, and the valence band (E V ) levels are À7.96, À8.21, and À8.39 eV, respectively. [24,30,31,49] Linked with the optical bandgap value, the conduction bands (E C ) of SnO 2 , SnO 2 /indole, and SnO 2 /Cl-indole are measured to be À4.07, À4.33, and À4.51 eV, respectively. Figure 4d displays the corresponding energy levels of PSC functional layers.…”

“…Among them, 12.5° is the characteristic peak of the (001) crystal plane of excess PbI 2 , while the characteristic peak of the (110) crystal plane of the cubic crystal‐phase perovskite material at 13.7°. [ 30 ] No peak movement is observed in the XRD spectra, and no new peaks are observed, denoting that the crystal structure of the perovskite film does not change after Cl‐indole or indole modification. However, the intensity of diffraction peaks on the perovskite film grown on the indole and Cl‐indole‐modified layer is stronger, denoting that the crystallinity of the perovskite material is effectively improved.…”

Nicotinamide‐Modified PEDOT:PSS for High Performance Indoor and Outdoor Tin Perovskite Photovoltaics

“…With the doping of these materials can significantly control the film morphology and enhance the crystallinity. [19] For tin-based perovskite, a small amount of doping can properly optimize the level matching, but it is difficult to improve the level mismatch of the whole device. Meanwhile, according to the perovskite tolerance factor formula, when the doping amount of the active layer increases, the intrinsic defects introduced by doping will become more obvious, which has the opposite effect.…”

Boric acid improves the stability of perovskite solar cell precursor solution

“…快速滴加 400μL 乙醚。将 制备好的薄膜在 150 ℃下退火 10 min。然后旋涂 30 µL Spiro-OMeTAD 溶液(3000 rpm, 30 s)作为空穴传 ) 。 Figure 2 The calculated content of by-product MFAI from the 1 H NMR results in the perovskite solution with different stabilizer aging for 1d and 5 d, respectively. 添加 HCl 和 HI 的溶液老化 5 天后，MFAI 的含 量分别约为 0.5 mol%和 2.2 mol%，可见 MFAI 的生 成受到了明显的抑制。但在强酸条件下，大量的 I -被 DMSO 溶剂氧化成 I2，溶液的颜色变成了红褐色 (见图 S15)。本文又尝试在前驱体溶液中加入弱酸--乙酸(HOAc)，但是 HOAc 不仅没有抑制副反应， 甚至加速了副反应的发生。溶液老化 5 天后，MFAI 的比例竟然高达 12.7 mol%。分析其原因是在 DMSO 溶液中，HOAc 和 MA + 的 pKa 值分别为 12.6 和 11.1， 轨道信 号的结合能为 138.03 eV，而在添加 BA 稳定剂的钙 钛矿膜中为 138.17 eV，相应的 Pb 4f5/2 轨道信号从 142.89 eV 移动到 143.03 eV(图 3c)，这表明加入 BA 后，Pb 4f 轨道的结合能变大。薄膜中 B 1s 轨道的结 合能则由原始 BA 粉末中的 193.60 eV 减小为 190.78 eV(图 3d)。 研究表明， 当添加剂与 I 离子发生作用时， 会导致 Pb 4f 轨道电子云密度减小， 结合能变大。[30][31][32] 结合薄膜中 B 1s 轨道的结合能降低， 证明硼酸中的 B 与 I 发生了配位作用，改善了溶液稳定性。…”