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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.

In recent years, high-efficiency solar cells have a strong competitiveness in the market and the p-type PERC solar cell is the mainstream product of leading cell manufacturers. To further improve the efficiency and reduce the cost, laser doping selective emitter (LDSE) has been introduced into the mass production line as a promising technology. In this work, we fabricated high efficiency PERC solar cells by using LDSE technique. Firstly, we adjusted the diffusion process and obtained the best sheet resistance (115 ± 5 Ω/sq), which resulted in an efficiency gain of 0.11%. Subsequently, the best diffusion profile of the selective emitter was obtained through optimization. With the surface concentration of about 3.0×1020 atoms/cm3 and emitter depth of 0.32 µm, the optimum photovoltaic parameter gains have been achieved, namely 0.18% for Eff, 6.7 mV for Voc and 0.25 mA/cm2 for Jsc respectively. EQE measurements show that the spectral response can be improved in the short wavelengths through introducing LDSE structure. Correscan measurements indicate that the front contact resistance of SE solar cell was slightly higher than that of reference due to the lateral transport resistance. The efficiency of LDSE solar cell can be increased further by the optimization of laser uniformity and the alignment of screen-printed finger with heavily doped region.

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.

In this work, the industrial glass-glass module was developed using bifacial n-type solar cell. The passivation emitter and rear total diffusion cells (PERT) structure solar cell combined boron spin-on with POCl3 diffusion and double sides H-pattern screen printing metallization. With the assistance of the spin-on single side doping method, an average efficiency of 20% with 90% bifaciality was obtained in our laboratory, 6*10 cells bifacial glass-glass modules were fabricated in industrial line. The PID about 3.5% was obtained after 600 hrs under 85°C-85% humidity with a bias of -1000 V, while the LID was about 0.19% under the IEC standard of 60 kW·h/m2 illumination. As expected, power output gains of 15% on sand and 30% on snow were recorded for the glass-glass bifacial modules compared with mono-facial modules in our outdoor experiments.