Enhanced Light Harvesting in Perovskite Solar Cells by a Bioinspired Nanostructured Back Electrode

Abstract

perovskite materials. [1][2][3][4][5][6][7] Since 2009, rapid progress has been made on the performance of methylammonium lead halide perovskite (CH 3 NH 3 PbX 3 , X = Cl, Br, I)based PeSCs with a substantial increase in power conversion efficiency (PCE) from 3.8% to a stunning value of more than 22%. [8][9][10] Typically, a PeSC is composed of a perovskite absorber layer sandwiched between the hole and the electron transport layers (HTLs and ETLs, respectively). [11] Upon the absorption of incident light, carriers will generate in the perovskite absorber and transport to HTL or ETL, and finally are collected by the corresponding electrodes. To achieve highly efficient and low-cost PeSCs, great efforts have been devoted to optimizing the perovskite material design, device structures and relevant processing techniques. [1][2][3][4][5][6][7][8][9][12][13][14][15] Apart from the major emphasis on perovskite film processing and interface modification for efficient charge collection, it is still of great challenges to achieve maximum light trapping within the devices and then make the majority of incident light for photoelectric conversion. For instance, the photocurrent density of the reported PeSCs were still lower than the theoretical one of ≈26 mA cm −2 , [16] indicating that quite a large fraction of incident light still remains unused for photocurrent generation. The increased physical thickness of the perovskite absorber allows for better light absorption, which however certainly reduces the charge collection efficiency due to the increased recombination current. To alleviate this contradiction, light-trapping schemes are imperative for effectively enhancing light harvesting efficiencies in PeSCs by increasing the internal scattering and absorption of incident light with lower recombination currents.To date, numerous light manipulation strategies using periodic or random structures have been proposed such as plasmonic structures, [17] microlens array, [18] metal nanoparticles, [19] aperiodic arrays, [20][21][22] microresonators, [23] and optical cavities. [24,25] By introducing these schemes to the appropriate interfaces in thin-film solar cells, light absorption can be effectively enhanced by guiding and retaining the incident light through the enhancement of optical path length or the spatial redistribution of light intensity due to surface plasmon resonances (SPRs). Nevertheless, most of these schemes are limited for the practical adoption in large-area solar cell fabrication Light management holds great promise of realizing high-performance perovskite solar cells by improving the sunlight absorption with lower recombination current and thus higher power conversion efficiency (PCE). Here, a convenient and scalable light trapping scheme is demonstrated by incorporating bioinspired moth-eye nanostructures into the metal back electrode via soft imprinting technique to enhance the light harvesting in organic-inorganic lead halide perovskite solar cells. Comparedto the flat reference cell with a methylammonium le...

Moth-eye Structured Polydimethylsiloxane Films for High-Efficiency Perovskite Solar Cells

“…In previous work, we showed that the properties of PDMS can be applied effectively in photovoltaic devices [14]. Recent efforts to increase the PCE of PSCs have employed biomimetic multiscale architecture approaches [23][24][25][26]. However, these approaches were applied to conventional devices with irregular microstructures obtained through expensive and complex fabrication processes.…”

Emerging Novel Metal Electrodes for Photovoltaic Applications

“…In the subsequent work, they have incorporated the biomimetic moth‐eye structure and antireflection layer in the PTB7:PC 71 BM system, and achieved the PCE of 9.33% . Recently, Tang and co‐workers further reported the incorporation of the bioinspired moth nanostructure into back electrode in the PVSCs . The corrugated back electrode with bioinspired pattern induces a broadband polarization‐insensitive light scattering and surface plasmonic resonance, which outperform the control flat cell even in the periodic grating back electrode.…”

Optical Design in Perovskite Solar Cells

“…The periodic nanostructure can also be integrated into the organic ETL for better light harvesting. Tang et al reported the use of moth‐eye nanostructure patterned PCBM as the ETL for the p‐i‐n type PSCs through a nanoimprint process with prepatterned PDMS molds. Compared to the reference device with a flat PCBM layer, the device with moth‐eye patterned PCBM layer exhibits a remarkable enhancement in the light harvesting and thereby an increased J sc .…”