High-efficiency (>30%) monolithic perovskite-Si tandem solar cells with flat front-side wafers

Abstract

Perovskite-Si tandem solar cells are the most prominent contenders to succeed commercial single-junction Si cells that dominate the market today. Yet, to justify the added cost of inserting a perovskite cell on top of Si, the tandem devices should first exhibit sufficiently high power conversion efficiencies (PCEs). Here, we present two key developments with a synergetic effect that boost the PCEs of our tandem devices with front-side flat Si wafers - the use of 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPA) in the perovskite precursor ink that suppresses non-radiative recombination near the perovskite/C60 interface, and the use of SiO2 nanoparticles under the perovskite film that suppresses the enhanced number of pinholes and shunts introduced by pFBPA, while also allowing the use of [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid as a hole transport layer. Integrating a perovskite cell featuring these developments with a Si cell, reproducible PCEs of 30±1% and a certified maximum of 30.9% are achieved for an active area of 1cm2.

A Universal Perovskite/C60 Interface Modification via Atomic Layer Deposited Aluminum Oxide for Perovskite Solar Cells and Perovskite–Silicon Tandems

“…To improve the wetting of the perovskite precursor on Me-4PACz, 0.2% wt SiO x -np (20 nm diameter) solution in ethanol was spin-coated statically at 2000 rpm with 500 rpm s −1 acceleration followed by an annealing step of 10 min at 100 °C. [15] The absorber utilized in tandems was Cs 0.05 (FA 0.9 MA 0.1 ) 0.95 Pb(I 0.80 Br 0.20 ) 3 . The absorber was fabricated with one-step anti-solvent method.…”

“…The losses associated with the choice of the self-assembled monolayer can be mitigated by exchanging the molecules (e.g., MeO-2PACz, 2PACz, or Me-4PACz) and by reducing the contact area, for example, by introducing a partially continuous insulating nanoparticulate layer. [15][16][17][18][19][20][21][22][23][24][25][26][27][28] The losses imposed by C 60 are suppressed significantly upon insertion of AlO X , resulting in a ≈tenfold increase in the PLQY, allowing for a k B T/q × ln(10) ≈60 mV increase in V OC . A breakdown of the V OC losses is shown in Figure S7 (Supporting Information).…”

“…[7] General strategies include decreasing the fraction of defective contact area between perovskite and C 60 with wide bandgap dielectrics like LiF and MgF X [8][9][10][11] (similar to passivating contacts in silicon technology [12] ) or improving the band energetics via organic molecules like piperazinium iodide and 2,3,4,5,6-pentafluorobenzylphosphonic acid. [13][14][15] For PSCs, several surface treatments have been shown. However, most of them utilize spin-coated organohalides unsuitable for processing on top of textured surfaces and likely incompatible with large substrate dimension.…”

A universal perovskite/C60 interface modification via atomic layer deposited aluminum oxide for perovskite solar cells and perovskite-silicon tandems

“…Hence, addressing the perovskite/C60 interface to suppress the nonradiative recombination is of significant importance to exploit the potential of the p-i-n perovskite solar cells, especially since p-i-n devices are optically superior when employed in multi-junction devices 7 . General strategies include decreasing the fraction of defective contact area between perovskite and C60 with wide bandgap dielectrics like LiF and MgFX [8][9][10][11] (similar to passivating contacts in silicon technology 12 ) or improving the band energetics via organic molecules like piperazinium iodide and 2,3,4,5,6-pentafluorobenzylphosphonic acid [13][14][15] . For PSCs, several surface treatments have been shown.…”