Efficient semi-transparent perovskite quantum dot photovoltaics enabled by asymmetric dielectric/metal/dielectric transparent electrodes

CsPbI3 perovskite quantum dots (CsPbI3-PQDs) have a high potential as semi-transparent photovoltaic absorbers because of the facile control of film thicknesses, size-tunable optical band gaps, and nanometer-scale grain sizes suppressing light scattering. Conventional semi-transparent CsPbI3-PQD solar cells showed low photovoltaic performances due to the low electrical conductivity of the graphene electrodes. Here we report that dielectric/ ultra-thin metal/dielectric (DMD) electrodes with excellent optical transmittance and electrical conductivity deliver superior photovoltaic performances in the semi-transparent CsPbI3-PQD solar cells. Particularly, the asymmetric DMD electrodes composed of MoOx 15 nm/Au 10 nm/MoOx 35 nm (asym-MAM) stacks exhibit higher optical transmittance than that of the symmetric MoOx 15 nm/Au 10 nm/MoOx 15 nm (sym-MAM) stacks. The optical simulation confirms that asym-MAM stacks reduce the parasitic absorption loss in metal interlayers. Therefore, the asym-MAM stacks with a high electrical conductivity show a higher average visible transmittance (AVT) than that of the sym-MAM. Consequently, the semi-transparent CsPbI3-PQD solar cells fabricated using the asym-MAM transparent top electrodes show a power conversion efficiency of 11.3% with a considerable AVT values of 23.4% (400-800 nm) and 20.0% (380-780 nm), respectively, which were calculated from their transmittance spectra. This is the highest-efficiency semi-transparent PQD solar cells that can be used for solar window applications requiring an AVT value of over 20%.

Automated summary

CsPbI3 perovskite quantum dots (CsPbI3-PQDs) have potential in semi-transparent photovoltaic absorbers. Dielectric/ultra-thin metal/dielectric (DMD) electrodes with excellent optical transmittance and electrical conductivity improve the photovoltaic performances. Asymmetric DMD electrodes reduce parasitic absorption loss and show higher average visible transmittance (AVT) than symmetric ones, resulting in the highest-efficiency semi-transparent PQD solar cells for solar window applications requiring an AVT value of over 20%.