Donor–π–Acceptor Type Porphyrin Derivatives Assisted Defect Passivation for Efficient Hybrid Perovskite Solar Cells

Abstract

In recent years, hybrid perovskite solar cells (PSCs) have attracted much attention owing to their low cost, easy fabrication, and high photoelectric conversion efficiency. Nevertheless, solution‐processed perovskite films usually show substantial structural disorders, resulting in ion defects on the surface of lattice and grain boundaries. Herein, a series of D–π–A porphyrins coded as CS0, CS1, and CS2 that can effectively passivate the perovskite surface, increase VOC and FF, reduce the hysteresis effect, enhance power conversion efficiency to be higher than 22%, and improve the device stability is developed. The results in this study demonstrated that the donor–π–acceptor type porphyrin derivatives are promising passivators that can improve the cell performance of PSCs.

Review of Interface Passivation of Perovskite Layer

“…Many passivation molecules directly neutralize the surface charges or dangling bonds to annihilate the corresponding electron traps [ 98 , 99 , 100 ], e.g., by introducing Lewis bases (such as thiourea) to coordinate with Pb 2+ on the surface and grain boundaries to reduce the defect density; some electron trap states can accept one of the Lewis-based defects on the surface of the perovskite through the Lewis acid molecule electron to be reduced [ 62 , 101 , 102 , 103 , 104 ]. The molecular hydrophilic chemical group and perovskite molecule combine to form a coordination bond, which is conducive to the transport of carriers [ 60 , 105 , 106 ].…”

“…The molecular hydrophilic chemical group and perovskite molecule combine to form a coordination bond, which is conducive to the transport of carriers [ 60 , 105 , 106 ]. Furthermore, the introduction of molecules enhances the smoothness of the perovskite layer interface, increases the contact angle, reduces pores and defect states, and significantly improves the interface properties of the perovskite layer [ 98 , 107 ]. In addition, the energy level matching between the perovskite layer and the carrier transport layer is altered, and the light absorption range of the material is increased, thereby resulting in a higher Jsc and FF [ 108 , 109 ].…”

“…The existence of long alkyl chains prevents the penetration of water molecules into the air. The passivated device achieved a maximum efficiency of 22.37% [ 98 ].…”

Uniform Stepped Interfacial Energy Level Structure Boosts Efficiency and Stability of CsPbI2Br Solar Cells

“…The larger arcs of the Nyquist plots of 5CzBn‐ and 4t‐5CzBn‐based devices correspond to the larger recombination resistance ( R rec ), which indicates charge recombination is weaker in 4t‐5CzBn‐based device as compared with 5CzBn counterpart. [ 48 ] The fitted Nyquist plots of bare, 5CzBn, and 4t‐5CzBn‐based devices present R rec values of 931, 1665, and 3419 Ω cm –2 , respectively, indicating that the charge recombination in PSCs is suppressed by inserting an interlayer and the employment of a 4t‐5CzBn interlayer is more effective than 5CzBn. The results imply the small stepped energy level structure contributes to the efficient charge extraction and then reduces the energy loss in CsPbI 2 Br PSCs.…”

Thiamine additive engineering enables improved film formation towards high efficiency and moisture stability in perovskite solar cells

“…Currently, the highest certified power conversion efficiency (PCE) of devices has reached 25.5% [1]. However, the instability of the perovskite layer in the ambient environment (light illumination, heat treatment or moisture erosion) [2][3][4][5], and the existing defects seriously restrict the performance and limit its development towards practical applications and commercialization [6][7][8][9][10]. Among the various environmental factors that cause instability, moisture instability is a major obstacle because of its severe harmfulness, which causes hydrate formation, promoting the irreversible decomposition of perovskite accompanied by a sharp decline in optical absorption and severe electron-hole recombination [11,12].…”