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 (VOC) and short-circuit current (JSC) conditions. A mismatch between the internal quasi-Fermi level splitting (QFLS) and the external VOC 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-VOC mismatch, and boosting the VOC. 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 JSC, promoting charge extraction and raising the JSC. The combination of the n- and p-type optimizations allows us to approach the thermodynamic potential of the perovskite absorber layer, resulting in 1 cm2 devices with performance parameters of VOCs up to 1.29 V, fill factors above 80% and JSCs up to 17 mA/cm2, in addition to a thermal stability T80 lifetime of more than 3500 h at 85 °C.

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.

Despite the incredible progress made, the highest efficiency perovskite solar cells are still restricted to small areas (<1 cm 2 ). In large part, this stems from a poor understanding of the widespread spatial heterogeneity in devices. Conventional techniques to assess heterogeneities can be time consuming, operate only at microscopic length scales, and demand specialized equipment. We overcome these limitations by using luminescence imaging to reveal large, millimeter-scale heterogeneities in the inferred electronic properties. We determine spatially resolved maps of "charge collection quality", measured using the ratio of photoluminescence intensity at open and short circuit. We apply these methods to quantify the inhomogeneities introduced by a wide range of transport layers, thereby ranking them by suitability for upscaling. We reveal that top-contacting transport layers are the dominant source of heterogeneity in the multilayer material stack. We suggest that this methodology can be used to accelerate the development of highly efficient, large-area modules, especially through high-throughput experimentation.

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 VOC, 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 VOC 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.

In cryptography, the art of secret sharing, is to share among a group of selected few an individual share of the secret. Individual shares are of no use on their own. The multifaceted implementation of this scheme in literature including Shamir, Blakley and Asmuth-Bloom to name a few, has led to the emergence of higher computational complexity during both sharing and reconstruction and generates noise like shares. In order to come up with a meaningful sharing scheme, Lin and Tsai proposed a method that uses Steganography using Shamir's secret sharing scheme; again which led to high computational complexity. Therefore, in order to overcome the above problem, a new scheme is suggested which deploys simple graphical masking, done by simply ANDing, value substitution for share generation and reconstruction can be done by value re-substitution and then ORing the qualified set of shares. Also, this proposed method finally creates, meaningful shares by using Steganography; instead of noise like shares.