Fabrication, photovoltaic analysis, and electrical characterization of Au/ZnTPyP/p-Si/Ag heterojunction under gamma radiation effect for solar cell applications

Abstract The main objective of the current study is to investigate the impact of gamma rays on the characteristics and behavior of a fabricated heterojunction device based on tetra pyridyl-porphine zinc (ZnTPyP). The importance of this study includes determining critical parameters such as conversion efficiency (η). A cobalt-60 gamma source has been employed to investigate the effects of gamma exposure dosages ranging from 0 to 5 kGy on the morphological and optical features of the studied material. An atomic force microscope (AFM) was used to examine the morphological characteristics of the ZnTPyP film that formed on the glass substrate. The thin film’s optical characteristics were investigated on quartz for both as-deposited and irradiated films at various gamma doses (1 kGy and 3 kGy). Additionally, ZnTPyP is evaporated on p -type silicon substrates to create ZnTPyP/p-Si heterojunction. The current–voltage ( I – V ) curves at various doses of gamma radiation at 0, 1, 3, and 5 kGy for Au/ ZnTPyP /p-Si/Ag heterojunction device are experimentally measured. The predominant conduction processes are the thermionic emission and single-trap space-charge-limited current (SCLC). Furthermore, the values of the barrier height $$\left( {\varphi_{B} } \right)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mfenced> <mml:msub> <mml:mi>φ</mml:mi> <mml:mi>B</mml:mi> </mml:msub> </mml:mfenced> </mml:math> are estimated using two different methods, including I – V method and Norde’s equations at different doses, and their values are comparable. Under illumination at 0 kGy, we found the values of short-circuit current (Isc), open-circuit voltage (Voc), and photoconversion efficiency (η) to be 0.92 mA, 0.41 V, and 4.28%, respectively. On the hand, some important optical parameters are determined for both as-deposited and irradiated ZnTPyP films, such as skin depth (δ), and found that δ values reduce with increasing gamma doses, reflecting the efficiency and performance of photovoltaic cells. Finally, the study indicated the alteration in the studied optical parameters and slightly enhanced the Au/ZnTPyP/p-Si/Ag heterojunction efficiency when subjected to gamma radiation.