TARETTO Kurt Rodolfo
congresos y reuniones científicas
Potential of perovskite/HIT silicon solar cells: a realistic optical analysis based on current active and functional layer properties
Conferencia; 2nd International Conference on Perovskite Solar Cells and Optoelectronics; 2016
Heterojunction amorphous/crystalline silicon (HIT) solar cells holdthe currentefficiency record of 25.6% among the photovoltaictechnologies based on silicon [1]. Anovel route to surpass thisefficiency record without increasing significantly theproduction costsis preparing tandem perovskite/silicon cells. Perovskite subcells canbefabricated monolithically onto silicon with inexpensive methods suchas spin coatingand thermal evaporation [2,3] and can be interconnectedelectrically in series, i.e. twoterminals connection (2T), or with afour terminals (4T) configuration.In this work, we use thin filmoptics combined with incoherent light propagation inthick layers, e.g.silicon wafers, to model light absorption in tandemperovskite/HITsolar cells based on the layer stack prepared andcharacterized in [3] with a measuredphotocurrent of 14 mA/cm2 and astabilized efficiency of 18.1% in a 2T configuration.We analyze andpropose modifications on some characteristics of this tandemdevicelike the hole transport layer (HTL), the collection efficiencyof the intrinsic amorphoussilicon (a-Si) layers, the electricalinterconnection, the inclusion of a back contact lightdiffuser and thefree choice of silicon thickness between 1 μm and 500 μm.Thephotocurrent delivered by each subcell is calculated assuming thateachphotogenerated electron-hole pair is extracted by thecorresponding contact with perfectcarrier collection efficiency. Giventhe large amount of functional layers to beoptimized, a simulatedannealing optimization algorithm is used to find the optimumlayerthicknesses that maximize the efficiency.Our simulation resultssuggest that replacing the traditional organic spiro-OMeTADHTL byinorganic materials such as NiO and CuSCN, can add up to 0.8 mA/cm2 tothephotocurrent due to the higher transparency of these materials inthe wavelength rangeof 350-450 nm. In the optimized cells, thecontribution of the a-Si layers in the HIT cellis smaller than 5% ofthe photocurrent. Using real device fill factor and opencircuitvoltages of record perovskite and HIT cells we obtain anefficiency of 28.7% for 4Ttandem configuration with a 250 μm siliconwafer, 350 nm perovskite, 400 nm CuSCNHTL and a perfect rear lightdiffuser. The simulations reveal that in the optimizeddevices thefront surface reflection accounts for a photocurrent loss of 6 mA/cm2andthe parasitic absorbance of the contact layers adds up to aphotocurrent loss of4 mA/cm2. This implies that an efficiency beyond30% is within reach with a frontsurface texture capable of reducingthe reflection.References[1] K. Masuko, M. Shigematsu, T. Hashiguchi,et al., IEEE J. Photovolt. (2014), 4,1433.[2] J. Werner, C.-H. Weng,A. Walter, et al., J. Phys. Chem. Lett. (2015), 7, 161.[3] S.Albrecht, M. Saliba, J.P.C. Baena, et al., Energy Environ. Sci.(2016), 9, 81