  A direct, camera-based implied open-circuit voltage (iVOC) imaging method via
the novel use of a single bandpass filter (s-BPF) is developed for large-area
photovoltaic solar cells and solar cell precursors. This method images the
photoluminescence (PL) emission using a narrow BPF with centre energy in the
high-energy tail of the PL emission taking advantage of the close-to-unity
absorptivity of typical photovoltaic devices with low variability in this
energy range. As a result, the exact value of the sample's absorptivity within
the BPF transmission band is not required. The use of a s-BPF enables the
adaptation of a fully contactless approach to calibrate the absolute PL photon
flux for camera-based spectrally-integrated imaging tools. The method
eliminates the need for knowledge of the imaging system spectral response and
the use of the emission and excitation spectral shapes. Through an appropriate
choice of the BPF centre energy, a range of absorber compositions or a single
absorber with different surface morphologies (e.g., planar vs textured) can be
imaged, all without the need for additional detection optics. The feasibility
of this s-BPF method is first assessed using a high-quality
Cs0.05FA0.79MA0.16Pb(I0.83Br0.17)3 perovskite neat film. The error in iVOC is
determined to be less than 1.5%. The efficacy of the method is then
demonstrated on device stacks with two different perovskite compositions
commonly used in single-junction and monolithic tandem solar cells.
