ORCID Profile
0000-0002-7942-293X
Current Organisation
University of Oxford
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Publisher: Springer Science and Business Media LLC
Date: 20-02-2023
DOI: 10.1038/S41467-023-36141-8
Abstract: In this work, we couple theoretical and experimental approaches to understand and reduce the losses of wide bandgap Br-rich perovskite pin devices at open-circuit voltage (V OC ) and short-circuit current (J SC ) conditions. A mismatch between the internal quasi-Fermi level splitting (QFLS) and the external V OC is detrimental for these devices. We demonstrate that modifying the perovskite top-surface with guanidinium-Br and imidazolium-Br forms a low-dimensional perovskite phase at the n -interface, suppressing the QFLS-V OC mismatch, and boosting the V OC . Concurrently, the use of an ionic interlayer or a self-assembled monolayer at the p -interface reduces the inferred field screening induced by mobile ions at J SC , promoting charge extraction and raising the J SC . The combination of the n- and p- type optimizations allows us to approach the thermodynamic potential of the perovskite absorber layer, resulting in 1 cm 2 devices with performance parameters of V OC s up to 1.29 V, fill factors above 80% and J SC s up to 17 mA/cm 2 , in addition to a thermal stability T 80 lifetime of more than 3500 h at 85 °C.
Publisher: Wiley
Date: 07-06-2023
Abstract: Metal halide perovskite based tandem solar cells are promising to achieve power conversion efficiency beyond the theoretical limit of their single‐junction counterparts. However, overcoming the significant open‐circuit voltage deficit present in wide‐bandgap perovskite solar cells remains a major hurdle for realizing efficient and stable perovskite tandem cells. Here, a holistic approach to overcoming challenges in 1.8 eV perovskite solar cells is reported by engineering the perovskite crystallization pathway by means of chloride additives. In conjunction with employing a self‐assembled monolayer as the hole‐transport layer, an open‐circuit voltage of 1.25 V and a power conversion efficiency of 17.0% are achieved. The key role of methylammonium chloride addition is elucidated in facilitating the growth of a chloride‐rich intermediate phase that directs crystallization of the desired cubic perovskite phase and induces more effective halide homogenization. The as‐formed 1.8 eV perovskite demonstrates suppressed halide segregation and improved optoelectronic properties.
Publisher: American Chemical Society (ACS)
Date: 21-09-2023
Publisher: Wiley
Date: 22-05-2023
Abstract: Mixed lead‐tin (Pb:Sn) halide perovskites are promising absorbers with narrow‐bandgaps (1.25–1.4 eV) suitable for high‐efficiency all‐perovskite tandem solar cells. However, solution processing of optimally thick Pb:Sn perovskite films is notoriously difficult in comparison with their neat‐Pb counterparts. This is partly due to the rapid crystallization of Sn‐based perovskites, resulting in films that have a high degree of roughness. Rougher films are harder to coat conformally with subsequent layers using solution‐based processing techniques leading to contact between the absorber and the top metal electrode in completed devices, resulting in a loss of V OC , fill factor, efficiency, and stability. Herein, this study employs a non‐continuous layer of alumina nanoparticles distributed on the surface of rough Pb:Sn perovskite films. Using this approach, the conformality of the subsequent electron‐transport layer, which is only tens of nanometres in thickness is improved. The overall maximum‐power‐point‐tracked efficiency improves by 65% and the steady‐state V OC improves by 28%. Application of the alumina nanoparticles as an interfacial buffer layer also results in highly reproducible Pb:Sn solar cell devices while simultaneously improving device stability at 65 °C under full spectrum simulated solar irradiance. Aged devices show a six‐fold improvement in stability over pristine Pb:Sn devices, increasing their lifetime to 120 h.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for AKASH DASGUPTA.