Breaking 1.7V open circuit voltage in large area transparent perovskite solar cells using bulk and interfaces passivation.

Abstract

Efficient semi-transparent solar cells can trigger the adoption of building integrated photovoltaics. Halide perovskites are particularly suitable in this respect owing to their tunable bandgap. Main drawbacks in the development of transparent perovskite solar cells are the high Voc deficit and the difficulties in depositing thin films over large area substrates, given the low solubility of bromide and chloride precursors. In this work, we develop a 2D and passivation strategies for the high band-gap Br perovskite able to reduce charge recombination and consequently improving the open-circuit voltage. We demonstrate 1cm2 perovskite solar cells with Voc up to 1.73 V (1.83 eV QFLS) and a PCE of 8.2%. The AVT exceeds 70% by means of a bifacial light management and a record light utilization efficiency of 5.72 is achieved, setting a new standard for transparent photovoltaics. Moreover, we show the high ceiling of our technology towards IoT application due to a bifaciality factor of 87% along with 17% PCE under indoor lighting. Finally, the up-scaling has been demonstrated fabricating 20cm2-active area modules with PCE of 7.3% and Voc per cell up to 1.65V.

Flexible, Transparent, and Bifacial Perovskite Solar Cells and Modules Using the Wide-Band Gap FAPbBr3 Perovskite Absorber

“…The average photoluminescence spectra, depicted in Figure d, reveal a gradual decrease in absolute intensity after the addition of the HTL. Additionally, a slight blue shift in the photoluminescence maximum position is observed, potentially induced by the presence of organic passivation cations derived from chloride salts added at the interface Figure e presents a comparison of optical data acquired on stacks and electrical data acquired on full devices.…”

“…An absorptivity model, corresponding to an ideal root squared absorptivity convolved with sub-band gap tail states, was employed, as established in the formalism developed by Katahara and Hillhouse whose use was already reported in previous studies. , The reference sample exhibited a QFLS of 1.83 eV, while the incorporation of a transport layer led to the emergence of nonradiative recombination, resulting in a decrease of this parameter to 1.81 and 1.78 eV for PTPD and PTAA, respectively. These values align with those recently reported for transparent high-band gap perovskite solar cells . Notably, the samples exhibited a high level of homogeneity with standard deviations on the order of 0.003 eV or less for the perovskite sample.…”

“…Neopentylammonium chloride and isopentylammonium chloride (1 mg of each) were dissolved in 1 mL of isopropyl alcohol and spin-coated on the perovskite layer to passivate defects as reported in our previous work . For PTAA and PTPD, a 10 mg/mL solution in toluene containing 10 μL/mL TPB and 5 μL/mL Li-TFSI salt (170 mg/mL in acetonitrile) was deposited at 4000 rpm for 20 s. Finally, 150 nm of ITO was sputtered on top using power using an industrial in-line magnetron sputtering (KENOSISTEC S.R.L., KS 400 In-Line) with the same procedure as our previous studies. , For modules, P1, P2, and P3 etching processes have been performed by using a raster scanning laser (Wophotonics, Yb:KGW, λ = 355 nm, 5 ps, pulsed at 2000 kHz with a fluence per pulse for patterning cells and for P1, P2, and P3 of 34.33, 18.06, and 16.68 mJ cm –2 , respectively). P2 is performed by placing six lines beside different fluences of ∼1 mJ cm –2 difference, with an average fluence per pulse of 18.06 mJ cm –2 .…”

“…Among the strategies to increase the AVT are thickness tuning, patterning, and band gap tuning. ,, The optimal band gap range to achieve AVT values of 50–80% with the band gap tuning strategy is 2.18 and 2.32 eV . Formamidinium lead bromide (FAPbBr 3 ) perovskite, which has a band gap of around 2.3 eV, falls well within the optimal band gap range for achieving high AVT and has already demonstrated AVT values exceeding 50%. , The PCE of opaque FAPbBr 3 solar cells typically reaches around 10%. − However, when using semitransparent back-contact, PCE decreased to approximately 8%. ,, This reduction in efficiency is primarily attributed to the lack of back-reflection of the metallic back-contact, which results in a reduced collection of backscattered light for harvesting. Furthermore, semitransparent solar cells often employ a thinner absorber layer to enhance the AVT of the cell.…”