Triazine-Substituted Zinc Porphyrin as an Electron Transport Interfacial Material for Efficiency Enhancement and Degradation Retardation in Planar Perovskite Solar Cells

Abstract

Motivated by the excellent electron-transfer capability of porphyrin molecules in natural photosynthesis, we introduce here the first application of a porphyrin compound to improve the performance of planar perovskite solar cells. The insertion of a thin layer consisting of a triazine-substituted Zn porphyrin between the TiO2 electron transport layer and the CH3NH3PbI3 perovskite film significantly augmented electron transfer toward TiO2 while also sufficiently improved the morphology of the perovskite film. The devices employing porphyrin-modified TiO2 exhibited a significant increase in the short-circuit current densities and a small increase in the fill factor. As a result, they delivered a maximum power conversion efficiency (PCE) of 16.87% (average 14.33%), which represents a 12% enhancement compared to 15.01% (average 12.53%) of the reference cell. Moreover, the porphyrin-modified cells exhibited improved hysteretic behavior and a higher stabilized power output of 14.40% compared to 10.70% of the reference devices. Importantly, nonencapsulated perovskite solar cells embedding a thin porphyrin interlayer showed an elongated lifetime retaining 86% of the initial PCE after 200 h, while the reference devices exhibited higher efficiency loss due to faster decomposition of CH3NH3PbI3 to PbI2.

Device Physics of the Carrier Transporting Layer in Planar Perovskite Solar Cells

“…The improvement of the morphology and crystallinity of the perovskite film leads to the significant increment of the short‐circuit (SC) current densities and a slight improvement in the fill factor toward the maximum PCE of 16.87% with the stabilized PCE of 14.40%. As shown in Figure c, the micro‐photoluminescence (PL) above 788 nm excitation reveals a clear difference in the PL signal between the TiO 2 based perovskite film and porphyrin‐modified TiO 2 ‐based perovskite film after the exposure to air for 2 h, 1 d, and 10 d, and the moderate enhancement of the integrated PL intensity signal of the porphyrin‐modified TiO 2 film presents an elevated stability compared with the reference pristine TiO 2 film . After 200 d, the nonuniform PL signal has been attributed to the decomposition of the perovskite film, where the intact area (denoted as 200 d (I)) shows high PL signal compared with negligible signal for the area degraded into PbI 2 (denoted by 200 d (P)).…”

A Review on Emerging Efficient and Stable Perovskite Solar Cells Based on g-C3N4 Nanostructures

“…Other challenges in the field of PSCs are the thermal and chemical stability [ 78 ] of the constituent materials and the overall device, hysteresis phenomenon [ 79 , 80 ], intrinsic and surface defects [ 81 , 82 ], enhanced charge carriers’ mobility and lead’s toxicity. Towards the mitigation of these problems a number of material and interface engineering approaches have been proposed including the integration of reduced graphene oxide as additive in the ETL, the perovskite and the HTL, the passivation of the ETL’s surface with metallated porphyrins and organic dyes, the modification of the titania ETL with transition metals, such copper and niobium, the passivation of perovskite layer’s surface with formamidinium iodide solution in isopropyl alcohol, and the addition of 4-tert-butylpyridine (tBP) in perovskite precursor as surface modification agent [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. The incorporation of graphitic carbon nitride has been proved to be an efficient method for controlling crystal growth, passivating defects and reducing charge carriers’ recombination rate, and, thus, confronting many of the above-mentioned challenges.…”

“…Research interventions aiming for further development of these photovoltaic devices have in common the integration of innovative nanostructured materials in order to increase their PCE, improve their long-term stability and decrease their fabrication cost. Among this purpose, several strategies, such as materials and interface engineering [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ], have been reported.…”

Dye Engineered Perovskite Solar Cells under Accelerated Thermal Stress and Prolonged Light Exposure

“…Thus, we employed a triphenylamine‐based metal‐free organic dye, namely (E)‐3‐(5‐(4‐(bis(2′,4′‐dibutoxy‐[1,1′‐biphenyl]‐4‐yl) amino) phenyl) thiophen‐2‐yl)‐2‐cyanoacrylic acid (D35) to modify the perovskite/titania interface. D35 and in general the dye sensitization approach has been recently used by our group in planar PSCs offering increased efficiency and improved stability in shelf‐shield conditions. Subsequently, its role was further investigated against thermal and light stresses.…”