Semi-Transparent Perovskite Solar Cells: Performance and Perspectives

We present the results of optical and electrical characterization measurements performed on a batch of semi-transparent Perovskite Solar Cells (PSCs) with the following direct (n-i-p) planar structure: FTO/TiO2:SnO2/FAPbBr3/PTAA/ITO, where FAPbBr3 is Formamidinium Lead Bromide perovskite and PTAA is Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]; cell encapsulation was obtained by lamination with Kapton foil. Cell performance was assessed for three different doping compositions (“REF”, “F4TCNQ”, “REF”+”F4TCNQ”) of the PTAA layer and for varying perovskite layer thickness; “REF” is the reference doping composition, which consists of LiTFSI (Lithium bis(trifluoromethanesulfonyl)imide) and TBP (4-tert-Butylpyridine), while “F4TCNQ” is 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyano-quinodimethane. A series of IV (“dark” and “light”) and EQE measurements were performed with the aim of obtaining an initial reference characterization, which is necessary because of the expected cell degradation, for all the samples in the batch. The measurements were performed considering different parameters and conditions; for example, varying light-chopping frequencies were used to evaluate the variation in the EQE measurement output. Furthermore, transmittance measurements were performed and compared, in relation to the differences in PTAA layer doping and perovskite thickness, for a preliminary suitability assessment of PSCs in the context of potential agrivoltaic applications. Subsequently, the same transmittance data was used to estimate the required performance (in terms of power generation/efficiency) of such perovskite structures, in the context of a perovskite/silicon tandem cell, needed to compensate for the diminished performance of the underlying silicon structure, and thus justify (at least, in terms of energy generation) the choice of such a device structure.