Inverted MAPbI3 Perovskite Solar Cells Based on Optimized NiOx Hole-Transporting Material and an Interlayer of Photovoltaic Polymers Exhibit a Power Conversion Efficiency over 21% with an Extended Stability Inverted MAPbI3 Perovskite Solar Cells Based on Optimized NiOx Hole-Transporting Material and an Interlayer of Photovoltaic Polymers Exhibit a Power Conversion Efficiency over 21% with an Extended Stability AITranslate

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DOI：https://doi.org/10.1021/acsaelm.3c01318

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Five mixing molar ratios, 1:0.6, 1:0.8, 1:1.0, 1:1.2, and 1:1.4, of conventional nickel(II) bis(acetylacetonate) (Ni(acac)2) and a diethanolamine (DEA) stabilizer have been tried for preparing precursor solutions in a sol–gel process for preparing the nickel(II/III) oxide (NiOx) hole-transporting material (HTM) in inverted methylammonium lead(II) triiodide (MAPbI3)-based perovskite solar cells (PVSCs). Considering both the electronic property and the homogeneity of NiOx thin films, a 1:0.8 molar ratio of Na(acac)2 and DEA in precursor solutions has been found to be optimal for the power conversion efficiency (PCE) up to 19.54% without any dopant in NiOx or the interlayer between NiOx and MAPbI3. Three cyano group-containing photovoltaic polymers, benzodithiophenylenevinylenethienothiophenylenevinylene-based pBαCN, diketopyrrolopyrrolequaterthiophene-based P4TDPPCN, and isoindigoquaterthiophene-based P4TICN, were chosen as the interlayer to further improve the PCE of NiOx-optimized PVSCs. The polymer interlayer-containing PVSCs exhibit a PCE as high as 20.09 and 21.43% (with a device active area of 0.04 cm2) for P4TDPPCN and P4TICN, respectively. We have experimentally verified that charge transport resistance (Rct), charge recombination resistance (Rrec), and trap density (ntrap) are all reduced with the polymer interlayer in PVSCs. The contact of the MAPbI3 perovskite to NiOx becomes better with a polymer interlayer in between. All of these enable the FF of PVSCs approaching 80%. Interestingly, the photovoltaic polymers provide additional photocurrent for the MAPbI3 PVSCs with a high short-circuit current density (JSC) over 24 mA/cm2. While MAPbI3 failed to deposit on the pBαCN polymer interlayer due to a serious nonwetting issue, it was relatively problem-free for P4TDPPCN and P4TICN. In this report, we provide chemical insight to explain the successful fabrication of the perovskite material on top of the P4TDPPCN or P4TICN polymer interlayer.