Design of an Inorganic Mesoporous Hole‐Transporting Layer for Highly Efficient and Stable Inverted Perovskite Solar Cells

Abstract

The unstable feature of the widely employed organic hole‐transporting materials (HTMs) (e.g., spiro‐MeOTAD) significantly limits the practical application of perovskite solar cells (PSCs). Therefore, it is desirable to design new structured PSCs with stable HTMs presenting excellent carrier extraction and transfer properties. This work demonstrates a new inverted PSC configuration. The new PSC has a graded band alignment and bilayered inorganic HTMs (i.e., compact NiOx and mesoporous CuGaO2). In comparison with planar‐structured PSCs, the mesoporous CuGaO2 can effectively extract holes from perovskite due to the increased contact area of the perovskite/HTM. The graded energy alignment constructed in the ultrathin compact NiOx, mesoporous CuGaO2, and perovskite can facilitate carrier transfer and depress charge recombination. As a result, the champion device based on the newly designed mesoscopic PSCs yields a stabilized efficiency of ≈20%, which is considered one of the best results for inverted PSCs with inorganic HTMs. Additionally, the unencapsulated PSC device retains more than 80% of its original efficiency when subjected to thermal aging at 85 °C for 1000 h in a nitrogen atmosphere, thus demonstrating superior thermal stability of the device. This study may pave a new avenue to rational design of highly efficient and stable PSCs.

Deepening the Valance Band Edges of NiOx Contacts by Alkaline Earth Metal Doping for Efficient Perovskite Photovoltaics with High Open‐Circuit Voltage

“…The Sr:NiO x films achieved a maximum VBM downshift value of 0.30 eV compared with the pristine NiO x . Figure b shows the energy diagram of the PSCs, in which the energy levels of FTO, MAPbI 3 , PC 61 BM, BCP, and Ag were generally accepted values from the literature . Clearly, deeper VBM of the HTLs can better align the band structures at the NiO x /MAPbI 3 interface, which is beneficial to hole extraction and reducing the loss of photocarrier accumulated at the interface of MAPbI 3 and HTLs …”

“…MAPbI 3 perovskite films based on doped NiO x HTLs show much more efficient PL quenching than that based on the pristine NiO x , indicating its enhanced hole extraction and transport efficiency (Figure c). As shown in Figure d, the PL decay curves of the samples were fitted with phenomenological biexponential functions: y = y 0 + A 1 exp[−( x − x 0 )/τ 1 ] + A 2 exp[−( x − x 0 )/τ 2 ] to obtain decay lifetimes . The average carrier lifetimes ( τ 0 ) of MAPbI 3 perovskite films with the pristine NiO x , Mg:NiO x , Ca:NiO x , Sr:NiO x , and Ba:NiO x HTLs were fitted to be 4.89, 1.69, 1.57, 1.44, and 3.66 ns, respectively, which were consistent with steady‐state PL results.…”

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

“…The PL quenching was more efficient for the perovskite film on NiO NW-6 hH SC (Figure 3c), suggesting betterc harge transport/extraction ability and an interfacialt rap passivation effect. [17,32] The corresponding EIS spectra are shown in Figure 3d and the fitting equivalent circuit and relatedd ata are also provided in Figure S4 and Ta ble S1.N otably,t he high-frequency and low-frequency region corresponded to the charget ransfer resistance (R ct )a nd recombination resistance( R rec ), respectively. [40] Al ower R ct and higher R rec were achieved for the NiO NW-6 hd evice, indicating faster and more efficient charge transfer/extraction at the NiO/ perovskite interface.…”

“…[11][12][13][14][15] Such NiObased devices exhibit excellent long-term moisture and thermal stability. [16][17][18] However,t oo ur knowledge, the majority of recentw ork has focusedo nd oping NiOt of urtheri mprovei ts intrinsicc onductivity for betterd evicep erformance. [19][20][21][22][23] As previously reported, this type of solution-based NCs are prone to aggregationa nd lead to ar ough or discontinuous filmm orphology, which would further create an imperfect NiO/perovskite interface.…”

Efficiency Improvement of Planar Inverted Perovskite Solar Cells by Introducing Poly 9,9‐Dioctyfluorene‐co‐benzothiazole into Polytriarylamine as Mixed Hole‐Transport Layer

“…To further explore the enhanced performance of the perovskite devices by the doping of F8BT, steady photoluminescence (PL) measurement of the perovskite films upon pure and mixed polymer HTLs was studied and shown in Figure b. Compared with the unmodified samples, PL quenching effect is observed in the perovskite films with F8BT‐doped PTAA HTL, implying more efficient charge carrier extraction and charge transfer using mixed polymer HTL . We also fabricated the hole‐only devices with the structure ITO/HTLs/perovskite/MoO 3 (10 nm)/Ag and shown in Figure c.…”