利用外量子效率研究太阳电池陷阱特性

USING EXTERNAL QUANTUM EFFICIENCY TO DETERMINE TRAP CHARACTERISTICS OF SOLAR CELLS

利用SRH（ShOCkley-Read—Hall）复合理论，建立一种新的测量太阳电池材料中陷阱特性的模型。该模型描述了晶体硅太阳电池基区中的电子陷阱能级相对位置（E1）、陷阱浓度（N1）、陷阱对空穴与电子的俘获截面的比值（σp／σn）与晶体硅太阳电池的开路电压、外量子效率之间的关系。通过测量在有偏置光源和无偏置光源情况下，单晶硅和多晶硅太阳电池在500～1050nm波长范围内单色光照射时的开路电压和外量子效率，计算出陷阱能级上电子浓度的变化量，从而获得电池基体材料中的陷阱特性。该方法可在室温下利用太阳电池量子效率测试系统进行测试，降低测量成本与测试复杂性，并且可扩展量子效率测试系统的应用。

A new method to measure trap characteristics in crystalline silicon solar cells is presented. Important parameters of traps including energy level, total concentration of trapping centers and capture cross-section ratio of hole to electron are deduced using the Shockley-Read-Hall theory of crystalline silicon solar cells in base region. Based on the as-deduced model, these important parameters of traps are determined by measuring open-circuit voltages of silicon solar cells under monochromatic illumination in the wavelength range 500-1050 nm with and without bias light. The effects of wavelength and intensity of bias light on the measurement results are also discussed. The measurement system used in our experiments is very similar to a quantum efficiency test system which is commercially available. Therefore, our method is very convenient and valuable for detecting deep level traps in crystalline silicon solar cells.