Inverted p-i-n perovskite solar cells based on a NiOx hole transport layer (HTL) are promising for large-scale panel production; however, interface-related energy losses and instability have limited their performance.
Researchers at China's Tsinghua University and CNNP Optoelectronics Technology (Shanghai) have introduced an ultrathin insulating polymethyl methacrylate (PMMA) interlayer at the buried interface between the NiOx HTL and the perovskite absorber. This interfacial modification effectively suppresses charge recombination, optimizes energetic alignments, and improves interfacial contact.
The polymer interlayer strongly improved the interfacial properties of NiOx/perovskite by minimizing the redox reaction and optimizing the interfacial energetics alignments between perovskite and NiOx layers.
X-ray photoelectron spectroscopy (XPS) showed that PMMA layers don't chemically react with the NiOx surface, but the cross-section SEM images revealed the reduction of voids and pinholes at the buried interface by inserting the PMMA layer. Ultraviolet photoelectron spectra indicated better energy level alignments facilitating the hole transfer and suppressing the interfacial non-radiative recombination.
With the insertion of ultrathin PMMA, the team successfully fabricated a small-scale PSC with a champion power conversion efficiency (PCE) of 22.2%, an open-circuit voltage (VOC) of 1.11 V, and an excellent operational stability.
Furthermore, the scientists successfully applied the PMMA layers on to 14 cm2 perovskite modules by slot die coating and achieved a PCE of 19.19% and a VOC of 6.95 V.
These findings highlight the effectiveness of interface engineering via ultrathin PMMA layers in enhancing both the performance and stability of NiOx -based PSCs, paving the way for their application in mass-produced large-area perovskite solar panels.
