High conductivity Ag-based metal organic complexes as dopant-free hole-transport materials for perovskite solar cells with high fill factors

Abstract

Two Ag-based metal organic complexes (HA1 and HA2) are employed as a new class of dopant-free HTMs for the application in PSCs. The cell based on HA1 achieved high PCE of 11.98% under air conditions, which is comparable to the PCE of the cell employing the doped spiro-MeOTAD (12.27%) under the same conditions.

Dopant‐Free Hole‐Transport Materials Based on Methoxytriphenylamine‐Substituted Indacenodithienothiophene for Solution‐Processed Perovskite Solar Cells

“…The HOMO energy levels of IDT–TPA (−4.9 eV) and IDTT–TPA (−5.0 eV) were determined using CV, whereas the LUMO energy levels ( IDT–TPA =−2.4 eV and IDTT–TPA =−2.5 eV) were determined using the UV/Vis absorption edge of the solution. The relative energy levels of the ETL, CH 3 NH 3 PbI 3 , and the HTMs are shown in Figure c. The HOMOs of IDT–TPA and IDTT–TPA were above that of CH 3 NH 3 PbI 3 (−5.4 eV), which provides sufficient driving force for the injection of holes from CH 3 NH 3 PbI 3 into the HTMs …”

“…The HOMOs of IDT-TPA and IDTT-TPA were above that of CH 3 NH 3 PbI 3 (À5.4 eV), which provides sufficient driving force for the injection of holes from CH 3 NH 3 PbI 3 into the HTMs. [31] Importantly,t he LUMO levels of IDT-TPA (À2.5eV) and IDTT-TPA (À2.4 eV) are highert han that of CH 3 NH 3 PbI 3 ,w hich should prevent electron transport from CH 3 NH 3 PbI 3 to the Au counter electrode and suppress carrier recombination. [32] These matched energy levels should preventt he depletion of holes within the perovskite and the accumulationo fh oles at the interface, reducing the opportunitiesf or charge recombination.…”

Enhancement of charge transport properties of small molecule semiconductors by controlling fluorine substitution and effects on photovoltaic properties of organic solar cells and perovskite solar cells

“…32–34 This type of D–A small molecule material often exhibits a high hole mobility and good conductivity with potential utility as a dopant-free hole transport material (HTM) in efficient perovskite solar cells (PSCs), which have recently emerged as promising photovoltaic devices. 35–38 Therefore, the rational molecular design of D–A structures has given rise to high-performance materials with physical properties that are appropriate for use in SM-OPVs as well as in PSCs. Thus far, a range of material designs have been presented and synthetic efforts have been applied toward controlling the optical, electrical and solid state assembly properties of a material by varying the D and A subunits to have different electron donating and accepting abilities.…”

Composite Hole‐Transport Materials Based on a Metal‐Organic Copper Complex and Spiro‐OMeTAD for Efficient Perovskite Solar Cells

“…Moreover, as in the case of Spiro‐OMeTAD, the electron density distribution of the HOMO in the CuH complex is delocalized over the whole molecule, while the electron density distribution of the LUMO is mainly located on the central bipyridine, spiro‐core segment. Hence, sufficient orbital overlap between HOMO and LUMO suggests that fast formation of neutral excitons and hole‐transfer transition may take place . The calculated hole re‐organization energies ( E R ) of CuH is 126 meV, which is much lower than that of Spiro‐OMeTAD (495 meV), indicating that CuH as hole‐transport material may show a faster hole‐transport rate in solar cell devices.…”

“…Generally, these materials have been developed for the use in solar cells as light absorbers, and for organic light‐emitting diodes (OLEDs) as emitters . Very recently, the use of two Ag‐based metal‐organic complexes and tetramethyl‐substituted Cu(II) phthalocyanine have been successfully applied to PSCs, thus pointing at the possible prospect for developing metal‐organic complexes as efficient HTMs for PSCs.…”