Bifacial Passivation of Organic Hole Transport Interlayer for NiO_x‐Based p‐i‐n Perovskite Solar Cells

Abstract

Methoxy‐functionalized triphenylamine‐imidazole derivatives that can simultaneously work as hole transport materials (HTMs) and interface‐modifiers are designed for high‐performance and stable perovskite solar cells (PSCs). Satisfying the fundamental electrical and optical properties as HTMs of p‐i‐n planar PSCs, their energy levels can be further tuned by the number of methoxy units for better alignment with those of perovskite, leading to efficient hole extraction. Moreover, when they are introduced between perovskite photoabsorber and low‐temperature solution‐processed NiO x interlayer, widely featured as an inorganic HTM but known to be vulnerable to interfacial defect generation and poor contact formation with perovskite, nitrogen and oxygen atoms in those organic molecules are found to work as Lewis bases that can passivate undercoordinated ion‐induced defects in the perovskite and NiO x layers inducing carrier recombination, and the improved interfaces are also beneficial to enhance the crystallinity of perovskite. The formation of Lewis adducts is directly observed by IR, Raman, and X‐ray photoelectron spectroscopy, and improved charge extraction and reduced recombination kinetics are confirmed by time‐resolved photoluminescence and transient photovoltage experiments. Moreover, UV‐blocking ability of the organic HTMs, the ameliorated interfacial property, and the improved crystallinity of perovskite significantly enhance the stability of PSCs under constant UV illumination in air without encapsulation.

Examining the Interfacial Defect Passivation with Chlorinated Organic Salt for Highly Efficient and Stable Perovskite Solar Cells

“…It indicates that the [BZTAm]Cl‐modified interface of perovskite/PC 61 BM can efficaciously suppress photogenerated charge carriers’ recombination and boost the interface contact characteristics, which further subsidize to improve the J SC and FF of PSCs. [ 49 ] The exceptional photovoltaic characteristics for PSCs modified with [BZTAm]Cl further show that the [BZTAm]Cl‐treated perovskite/PC 61 BM interfaces have stronger electron carrier migration and extraction proficiencies and indicate an uniform compact perovskite film with fewer surface defects, which is also profitable for the improvement of V OC of the devices. [ 17 ] For the further evidence of surface defects passivation by [BZTAm]Cl modification of perovskite film, we have conducted space charge limited current (SCLC) measurement, which is considered to be an effective technique to calculate the defect state density ( N trap ) in the perovskite film.…”

Barrier Designs in Perovskite Solar Cells for Long‐Term Stability

“…These materials can convert UV light to utilized visible light. Researchers have deposited UV barriers either as UV filter on the glass side of TCO glass substrate [76][77][78][79] or as a inter layer between TCO and perovskite absorber layer [80][81][82][83][84][85][86][87][88][89][90] to reduce the absorption of perovskite in the UV region, as indicated in Figure 2a. In the former case, for example, Bella et al coated the V570-doped fluoropolymer on the front surface of the device to convert UV light into visible light (Figure 2b), where the polymer shows strong absorption peak in the short-wavelength region and re-emits photons with wavelength red-shifted into the region with high incident photon-to-electron conversion efficiency (IPCE) ( Figure 2c).…”

“…Coupled with the improved interfacial property and perovskite crystallinity, a significantly enhanced UV illumination stability of PSC devices was achieved in air without encapsulation. [82] In addition to organic materials, carbon materials with advantageous absorption in UV region have also been used in PSCs to improve the UV stability. For example, PSCs with GO incorporated HTLs showed excellent full sun illumination stability because GO possesses proper absorption of light in the 300-400 nm region.…”

3 D NiO Nanowall Hole‐Transporting Layer for the Passivation of Interfacial Contact in Inverted Perovskite Solar Cells

“…To date, the most popular hole‐transporting material (HTM) has been poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). However, the disadvantages of high cost and undesirable device stability are inevitable for PEDOT:PSS‐based devices . Therefore, numerous efforts have been devoted to developing p‐type inorganic materials as candidates for stable and efficient HTMs.…”

“…However,t he disadvantages of high cost and undesirabled evice stabilitya re inevitable for PEDOT:PSS-basedd evices. [8][9][10] Therefore, numerous efforts have been devoted to developing p-type inorganic materials as candidates for stable and efficient HTMs.…”