I am not an expert in this field, but I am very interested and have researched to find an answer. I received some assistance from tlooto.com for this response. Could you please review the response below to see if it is correct?

Shallow energy levels, close to the conduction or valence band, are created by doping with elements having similar atomic sizes and valence structures, facilitating easy electron or hole excitation. Deep energy levels, introduced by dopants with different atomic properties, defects, or impurities, lie far from these bands and act as traps for charge carriers, reducing mobility and recombination rates by capturing and releasing carriers less frequently [1][2][4]. This separation extends carrier lifetime, decreasing charge carrier recombination and improving semiconductor device efficiency [3][5][6].

Reference

[1] Bertrandie, J., Han, J., Castro, C. S. P. D., Yengel, E., Gorenflot, J., Anthopoulos, T., Laquai, F., Sharma, A., & Baran, D. (2022). The Energy Level Conundrum of Organic Semiconductors in Solar Cells. Advanced Materials, 34.

[2] Kaake, L., Barbara, P., & Zhu, X. (2010). Intrinsic Charge Trapping in Organic and Polymeric Semiconductors: A Physical Chemistry Perspective. Journal of Physical Chemistry Letters, 1, 628-635.

[3] Alessandri, R., Sami, S., Barnoud, J., Vries, A. H., Marrink, S., & Havenith, R. (2020). Resolving Donor–Acceptor Interfaces and Charge Carrier Energy Levels of Organic Semiconductors with Polar Side Chains. Advanced Functional Materials, 30.

[4] Johnston, M., & Herz, L. (2016). Hybrid Perovskites for Photovoltaics: Charge-Carrier Recombination, Diffusion, and Radiative Efficiencies.. Accounts of chemical research, 49 1, 146-54 .

[5] Wen, X., Feng, Y., Huang, S., Huang, F., Cheng, Y., Green, M., & Ho-baillie, A. (2016). Defect trapping states and charge carrier recombination in organic–inorganic halide perovskites. Journal of Materials Chemistry C, 4, 793-800.

[6] Paulke, A., Stranks, S., Kniepert, J., Kurpiers, J., Wolff, C. M., Schön, N., Snaith, H., Brenner, T., & Neher, D. (2016). Charge carrier recombination dynamics in perovskite and polymer solar cells. Applied Physics Letters, 108, 113505.

thank you for your response. Information share here was already in my knowledge, However I was interested to now that how can we determine if a dopant has created shallow energy level or deep energy levels? How do these work to slow down recombination seprately.

thanks for sharing references @Park Sowon