Surface plasmon excitation in semitransparent inverted polymer photovoltaic devices and their applications as label-free optical sensors

Herein,we report on surface plasmon(SP)-sensitive semitransparent inverted polymer photovoltaic(PV)devices that are based on multilayered material systems consisting of poly(3-hexylthiophene):fullerene-derivative bulk-heterojunction PV layers and thin gold or silver anodes.We demonstrate that these PV devices allow the simultaneous generation of both electrical power and SPs on their anodes for photoexcitation just above the optical absorption edge of the PV layers,resulting not only in attenuated total reflection,but also in attenuated photocurrent generation(APG)under the SP resonance(SPR)condition.Moreover,we also confirm that the biomolecular interaction of biotin–streptavidin on the PV devices can be precisely detected via apparent SPR angle shifts in the APG spectra,even without the need for complex attenuated total reflection configurations.We highlight our view that APG measurements made using these PV devices show great potential for the development of future generations of compact and highly sensitive SPR-based optical sensors.

Flexible Crystalline-Silicon Photovoltaics:Light Management with Surface Structures

CONSPECTUS:Flexible solar cells have been intensively studied in recent years for their applicability on curved or uneven surfaces,which augments their versatility toward various applications.Although emerging materials such as organics/polymers,perovskite,amorphous silicon,and copper indium gallium selenide have been used as light absorption materials for flexible solar cells,the commercialization of these materials is limited owing to their efficiency degradation,usage of toxic materials,short lifespan,or scarcity.On the contrary,crystalline silicon(c-Si)solar cells have been commercialized because of their low manufacturing cost,long lifespan of over 20 years,and high power-conversion efficiency(PCE)of≤26.7%.However,the development of flexible solar cells using c-Si substrate poses an intrinsic problem resulting from its rigid material characteristics.In recent years,flexible solar cells using thin c-Si wafers have become more attractive with archiving a higher PCE than that of the emerging flexible solar cells.In addition,the mechanical flexibility can be realized using a thin c-Si film with a thickness of≤50μm,which is a quarter of the substrate thickness of conventional c-Si solar cells.Nonetheless,thin c-Si-based flexible solar cells face critical challenges because of severe light absorption loss in the entire wavelength region(300−1100 nm)because of the low absorption coefficient and surface reflection of c-Si.The development of the c-Si flexible solar cells should focus on improving the light absorption of thin c-Si films as well as maintaining the mechanical flexibility and stability of the thin c-Si solar cells.Thus,in this Account,we introduce high-aspect-ratio c-Si microwires and a random inverted-pyramidal-transparent optical film as promising surface structures for the efficient trapping of incident light in thin c-Si films.Moreover,the principles regarding the improvement in light absorption of these surface structures are discussed along with the implementable strategies for maximizing PCE of the c-Si flexible solar cells.Lastly,perspectives on further improvement of the PCE and stability of the flexible c-Si solar cells are presented.