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P-type multi-crystal (mc-Si) solar cells are facing relative weaker competitiveness compared to mono-crystal silicon solar cells due to the efficiency improvement bottleneck. To further enhance the efficiency of p-type mc-Si solar cells, we have systematically investigated the technology of hydrogenation with electron injection (HEI) on p-type mc-Si solar cells with different power conversion efficiency (PCE) grades. Experimental results manifested that the efficiency promotion of cells with higher efficiency (HE) was lower compared to that of lower efficiency (LE) cells under the same HEI processing condition, whether for conventional or passivated emitter and rear cells. Further investigations were carried out to prove that the effectiveness of HEI treatment was closely related to the concentration of both available hydrogen and defect in the bulk of solar cells. This highlighted that the lower concentration of available hydrogen was more helpful for HE cells to improve the electrical performances, which was contrary to LE cells due to the different distribution of defects in the bulk. Besides, programing analysis was implemented to optimize the HEI treatment scheme of HE cells, and the PCE was finally improved by 0.63%rel. ± 0.05%. This result provided an improved technological process to further improve the efficiency gains in the production process, where a classification method was introduced according to the efficiency distribution before HEI treatment. The proposed method can distribute solar cells into appropriate grades to avoid wasting resources in mass production. [ABSTRACT FROM AUTHOR]

The efficiency improvements of large area (244.34 cm2) crystalline silicon solar cells have been receiving significant attention, especially in high-efficiency multi-crystalline silicon (mc-Si) Passivated Emitter and Rear Contact (PERC) cells. The large area boron-doped mc-Si PERC cells were treated with hydrogenation for a different duration based on high-intensity infrared (HI-IR) LEDs of 940 nm. Compared to the boron-doped monocrystalline silicon (mono-Si) PERC cells, different trends of efficiency improvement were displayed after various hydrogenation duration. The results showed that the amplitude of the efficiency improvement was enhanced to the maximum around 8 min but then slowly decreased with the increasing hydrogenation duration. Moreover, we found that the iron-boron (Fe-B) pairs may occupy the dominant role in hindering the improvement of efficiency and the light-induced degradation (LID) after hydrogenation. The trend of efficiency improvement depended on the density of interstitial iron ions (Fe i +) and the formation and dissociation of Fe-B pairs. Therefore, a longer duration of hydrogenation was required for mc-Si PERC cells than for mono-Si PERC cells to enhance the efficiency and suppress the degradation. Additionally, the duration of hydrogenation was significantly shortened to 1 min when the pre-LID was applied, then the appropriate extension of the hydrogenation duration was more conducive to the efficiency improvement of mc-Si PERC cells. • The mc-Si PERC cells required a longer duration for hydrogenation. • The efficiency of mc-Si PERC cells appeared a loss, then gained steadily increase. • The reason for longtime hydrogenation of mc-Si PERC cells was due to Fe-B pairs. • The pre-LID was proposed to improve the efficiency loss and hydrogenation effect. [ABSTRACT FROM AUTHOR]

Light injection and cooling conditions can induce some differences in the temperature-raising time of multi-crystalline silicon (mc-Si) solar cells. Through real-time tracking and monitoring of sample surface temperature, the temperature-raising steps for achieving the optimum efficiency improvement and degradation mitigation were optimized and modified. Then the corresponding hydrogenation treatments under a high-intensity infrared LEDs source were carried out based on improved steps. The results indicated that the optimal temperature-raising time should be manipulated at around 60 s and then followed by a 2-min hydrogenation treatment. Furthermore, the temperature-raising process should keep the temperature rising continuously without interruption or temperature drop. However, excessive thermal treatment time damaged the formation of defect precursors and extended the hydrogenation time. Moreover, the Fourier Transform Infrared spectrum curves illustrated that the peak intensity of the Si–H bonds treated at the 60-s temperature-raising time was more significant than that of other temperature-raising time treatments. • Manipulated temperature-raising steps bring more efficient hydrogenation. • 60-s temperature-raising time and 2-min hydrogenation was optimum. • Excessive temperature-raising time damaged the formation of defect precursors. • 60-s temperature-raising time promoted the best peak intensity of Si–H bond. [ABSTRACT FROM AUTHOR]