Designing Hole Transport Materials with High Hole Mobility and Outstanding Interface Properties for Perovskite Solar Cells

Abstract

Organic–inorganic halide perovskite solar cells (PSCs) have attracted much attention due to their rapid increase in power conversion efficiencies (PCEs), and many efforts are devoted to further improving the PCEs. Designing highly efficient hole transport materials (HTMs) for PSCs may be one of the effective ways. Herein we theoretically designed three new HTMs (FDT−N, FDT−O, and FDT−S) by introducing a nitrogen‐phenyl group, an oxygen atom, and a sulfur atom into the spiro core of an experimentally synthesized HTM (FDT), respectively. And then we performed quantum chemical calculation to study their application potential. The results show that the devices with FDT−O and FDT−S instead of FDT may have higher open circuit voltages owing to their lower highest occupied molecular orbital (HOMO) energy levels. Moreover, FDT−S exhibits the best hole transport performance among the studied HTMs, which may be due to the significant HOMO‐HOMO overlap in the hole hopping path with the largest transfer integral. Furthermore, the results on interface properties indicate that introducing oxygen and sulfur atoms can enhance the MAPbI3/HTM interface interaction. The present work not only offers two promising HTMs (FDT−O and FDT−S) for PSCs but also provides theoretical help for subsequent research on HTMs.

Structural Engineering of FDT toward Promising Spiro-Typed Hole-Transporting Materials: Promoting the Hole Transport and Stabilizing the HOMO Levels

“…Herein, the lowest 50 excited states are considered for the vertical transitions. It should be noted here that the TD-DFT calculations are performed by considering the solvent effects of chlorobenzene because the experimental spectra are prepared in it, , and DCM is used for the ground-state geometrical optimizations because the experimental HOMO measurements are carried out in it. , Meanwhile, the emission wavelengths are obtained on the basis of the first excited-state structures. Accordingly, the Stokes shifts are calculated with the formula of Δλ st = λ em – λ abs , as shown in Table .…”

“…Compared with that of the spiro-OMeTAD, the hole mobility of X60 is improved, due to the oxygen atom modification of the spiro core . Meanwhile, theoretical studies reveal that the introduction of heteroatoms on the core scaffold of HTMs is an efficient strategy to promote the performance of PSCs. − Furthermore, the fluorinated isomeric analogues of spiro-OMeTAD, phenothiazine, and π-conjugated N -ethylcarbazole are also used to construct the highly efficient HTMs. ,− All the abovementioned investigations show that the heteroatom modification of the spiro-typed core is potentially helpful in improving the optoelectronic properties of HTMs.…”