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PERC solar cell passivated on the backside with AlOx and SiNx was introduced to construct the perovskite/silicon four-terminal tandem solar cell, because of its outstanding spectral response at the long wavelength region and much lower cost than SHJ and IBC. Different from the vast majority of the related reports, which were focused on the improvement of perovskite top cell, the silicon bottom cell was optimized here to promote the tandem efficiency. The central wavelength of antireflection was adjusted to further reduce the reflectance and enhance the spectral response of PERC cell in long wavelengths, in order to make the most of long-wavelength light transmitted through the perovskite top cell. Along with the increase of central wavelength, the external quantum efficiency of PERC cell at near-infrared wavelengths increases resulting in better short circuit current density and photoelectric conversion efficiency when filtered by the perovskite cell. A tandem efficiency gain of 0.07% (abs.) has been achieved. This report provides a facile way to improve the efficiency of perovskite/silicon four-terminal tandem solar cell based on the optimization of long-wavelength spectral response.

Multicrystalline silicon (mc-Si) PERC (passivated emitter and rear cell) solar cells suffer from severe light-induced degradation (LID), which mainly consists of two mechanisms, namely, BO-LID (boron&ndash, oxygen complex-related LID) and LeTID (light and elevated temperature induced degradation). The impact of thermal treatment on the LID of a mc-Si PERC solar cell is investigated in this work. The LID of mc-Si PERC solar cells could be alleviated by lowering the peak temperature of thermal treatment (namely sintering), perhaps because fewer impurities present in mc-Si tended to dissolve into interstitial atoms, which have the tendency to form LeTID-related recombination active complexes. The LID could also be effectively restrained by partially replacing the boron dopant with gallium, which is ascribed to the decreased amount of boron&ndash, oxygen (B&ndash, O) complexes. This work provides a facile way to solve the severe LID problem in mc-Si PERC solar cells in mass production.

Reactive ion etching technology was combined with passivated emitter & rear cell technology to reduce the reflectance and transmittance of incident light and improve the spectral response of polycrystalline silicon solar cell. Preconditioning with acid solution can induce the formation of worm-like structures on the front surface, which could bring about the reduction of reflectance and enhancement of spectral response in the visible range. Optimization of the capping layer thickness on the rear side can enhance the internal reflection, which will decrease the transmittance and promote the spectral response in long wavelength range.

Through simulation with PC1D software, it comes to a conclusion that low reflectance is essential to realize better photovoltaic performance, especially Jsc. Therefore, MACE texturing technology and double-layer antireflection coating were employed to reduce the reflectance of DWS polycrystalline silicon wafer. In order to inhibit the higher surface recombination velocity induced by submicrostructure texture, thermally grown oxide was introduced to enhance the passivation quality of SiNx:H. Finally, compared with the solar cell fabricated with traditional acid-based etching method, an efficiency gain of up to 0.49% (abs.) has been achieved.