J. Eur. Opt. Society-Rapid Publ. 22, 38( 2026) 379
whenever the cell is under indoor illumination, the absorption will be improved, also showing polarization sensitivity. This enhancement is characterized by a blue-shift in the peak absorbance from 650 nm in the planar structure to 615 nm in the nanostructure, achieving a closer spectral match to the 600 nm LED peak irradiance. Furthermore, the proposed PSC exhibits a slight but beneficial increase in absorbance in the spectral region corresponding to the secondary LED emission peak( 450 nm), which also significantly increases overall performance in that region. Thus, this nanostructure effectively enhances the overall absorbance in the spectral range from 400 nm to 650 nm, relative to the planar structure, while absorption decreases for k > 650 nm, signifying the successful achievement of spectral shape matching between the active layer absorbance profile and the LED irradiance spectrum within the critical operating interval. Other 2D structures have been tested, but as their results are close to the ones exposed here, significant limitations due to their difficult nanofabrication and integration into device architectures may reduce the feasibility of using them to improve these PSCs for indoor applications.
4 Conclusion
In this work, we first established a magnitude of interest that allows us to pinpoint the performance enhancement of a novel Pb-free Sn-based perovskite solar cell in an indoor room. We weigh the spectral absorbance of the cell by an irradiance spectrum, which is the average of a weighed efficiency, which is dependent on the lighting conditions around the cell. This leads to a simple figure of merit to understand the level of theoretical enhancement, by comparing the planar cell efficiency, taken as the reference case, with that of the cell with the proposed nanograting, as the improved one. To isolate the optical impact of the nanostructure, our model assumes constant electrical parameters, acknowledging that the electronic challenges of increased interfacial area are effectively addressed in experimental settings via surface passivation layers. Moreover, such nanogratings can facilitate improved carrier extraction by reducing the transport distance to the contacts, provided that conformal film deposition is achieved.
We have explored several geometries, achieving the best results with the use of 1D grating simulated in the device structure that was manufactured in one of our previous works. An optimized result is obtained at a geometrical form factor of the grid of h / w = 0.7 and a period of 190 nm. An average of 5.84 % optical enhancement( with a maximum of 7.09 % under x-polarization) confirms the feasibility of using nanograting-based Pb-free cells for indoor energy harvesting. In line with literature [ 23 ], our results suggest a proportional boost in electron-hole generation and short-circuit current, provided carrier extraction remains efficient. These results allow exploring Internet of Things applications where these cells can be used as energy harvesting photovoltaic devices, recycling ambient light to create fully autonomous wireless( but cloud-connected) systems.
Acknowledgments
A. B. thanks MICINN for the Ramon y Cajal Fellowship( grant No. RYC2021-030880-I).
Funding
This research was funded by Research Projects STEP-UP( TED2021-131600B-C31 and TED2021-131600B-C33), PLEDs( PID2022-140090OB-C21 and PID2022-140090OB-C22) and HyQuaNa( PID2022-137857NA-I00), financed by the Spanish Ministry of Science and Innovation MCIN / AEI / 10.13039- / 501100011033, STEP-UP also by the European Union“ NextGenerationEU”/ PRTR”, andPLEDsby“ ERDF A way of making Europe”.
Conflicts of interest The authors have nothing to disclose.
Data availability statement
There is an associated dataset available at: https:// doi. org / 10.21950 / J69M96.
Author contribution statement
Conceptualization, B. G-C, A. B., I. M., R. V., and A. G-M; Methodology, R. V., B. G-C, A. B., E. L-F and D. S.; Software, D. S.; Validation, Formal Analysis, Investigation and Resources: all authors; Data Curation, D. S., R. V.; Writing – Original Draft Preparation, R. V., B. G-C and D. S; Writing – Review Editing, Visualization, all authors; Supervision, Project Administration, Funding Acquisition, R. V.
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