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As a key to simulate electrostatic characteristics of solar cells and implement single-diode model into simulators, a noniterative parameter-extraction method is proposed to determine five parameters of single-diode model. It is straightforwardly derived from the transcend equation set of terminal ${I} - {V}$ equations to overcome the imperfections of poor efficiency in numerical iteration methods, low accuracy in semiempirical approaches, and absence of physical meaning in optimization algorithms. As a result, such a parameter-extraction method actually serves as a useful tool to acquire model parameters, analyze preparing process’ results, and expand practicability of lumped parameter model.

Three-diode lumped-parameter equivalent circuit model conforms to photovoltaic device physics and processes an exact analysis for ${I}$ – ${V}$ characteristics of industrial solar cells, because it explains the different leakage current components especially for recombination current resulting from defects or grain boundaries. However, three-diode model’s complete circuit topology leads to complicated transcendental ${I}$ – ${V}$ equation without analytical solution so that low computation efficiency limits three-diode model’s applications in photoelectric simulations. In this article, an effective-diode method is proposed to simplify three-diode model, derive accurate and efficient terminal current–voltage solution to three-diode model, and acquire electrostatic characteristics of the solar cells. The calculated values have good agreements with numerical iteration results and experimental data measured from solar cells, respectively. Finally, the effective-diode method performs an important role of solving three-diode model analytically, predicting ${I}$ – ${V}$ characteristics of industrial solar cells accurately, and providing three-diode model’s practicability and development in solar cells’ simulations.

A lumped-parameter circuit model is proposed to describe the S-shaped I-V characteristics with current kinks exhibited in perovskite solar cells (PSCs). The physics-based model represents the electrical effect of the electrode contact interface. A Difference-Microvariation (DM) principle is used to derive the explicit solution of the model, which gives accurate and efficient descriptions for the current kinks of PSCs in a single-piece formula. The good agreement between our proposed model and numerical iteration results or reconstructed experimental data proves its validity. We believe that, the improved model can provide optimization direction for device process. Meanwhile, the proposed DM principle can perform as an efficient and serviceable tool to implement the lumped-parameter model compactly into TCAD simulators of PSCs.

A parameter extraction routine for three-diode lumped parameter model of organic solar cells (OSCs) based on particle swarm optimization (PSO) is presented in this letter. In the process of parameter extraction by using PSO, we overcome the problem of encountering locally optimal solutions, where such a problem results from the similar effects of some parameters on ${I} - {V}$ characteristics. Combining with the analytical solution algorithm of OSCs’ three-diode lumped parameter model, our parameter extraction routine can efficiently acquire the accurate fitting parameters to complete simulations for ${I} - {V}$ characteristics. Furthermore, this routine is valid for the different algorithms of the solution to OSCs’ ${I} - {V}$ properties. Finally, we use the experimental data measured from OSCs to verify the parameter extraction routine. As a result, such a parameter extraction routine can perform as an important tool to extract the fitting parameters of OSCs’ lumped parameter model.

In this paper, we propose a method to analytically solve some types of DC lumped-parameter equivalent circuit models for solar cells with S-shaped I-V characteristics measured under illumination. Based on the models proposed previously by other authors, we present the set of equations describing solar cell’s terminal current and voltage, derive the analytical solutions of I-V characteristics, and give discussions about the effects from the model parameters on solar cells’ I-V characteristics. The comparisons between the proposed solutions and the least square method results illustrate that the solution calculation scheme is not only both accurate and efficient, but also valid in the whole operation regime of solar cells especially for the S-shaped kink in the first quadrant. Finally, the solutions are validated by the reconstructed experimental data to demonstrate that they can be adopted in the practical applications of solar cells. As a result, the feature of the proposed solutions can decrease computation complexity, ease the extraction process of the solar cells’ model fitting parameters, and increase simulation accuracy.

A lumped-parameter equivalent circuit model is proposed to simulate the S-shaped current–voltage ( ${I}$ – ${V}$ ) characteristics exhibited in organic solar cells. First, we derive an explicit terminal current solution as a function of terminal voltage from the equation set of the three-diode lumped-parameter model proposed by Mazhari. Second, we improved Mazhari’s model to improve the accuracy and developed the explicit solution of our improved model to improve the efficiency. Third, we use the method of least squares, Newton–Raphson root-finding scheme, and experimental data to validate the solutions of Mazhari’s and our models. As a result, owing to high accuracy and efficiency of computation, our explicit calculation scheme, regarded as a useful tool, can help to implement Mazhari’s and our models into photovoltaic device and system simulators in compact format.

A closed-form drain current compact model for amorphous oxide semiconductor (AOS) thin-film transistors (TFTs), including the influence from trapped charges, is presented in this paper. Accounting for both channel and interface trapped charges in this model, we explicitly solve the inherent closed-form surface potential by improving the computational efficiency of the effective charge density approach. Furthermore, based on the explicit solution of the surface potential, the expressions of the trapped and inversion charges in the channel film are derived analytically, and the drain current is integrated from the charge sheet model. Then, for the cases of the different operational voltages, the accuracy and practicability of our model are verified by numerical results of the surface potential and experimental data of the drain current in amorphous In-Ga-Zn-O TFTs, respectively. Finally, we give a discussion about the influence of the interface trapped charges on the device reliability. As a result, the model can be easily to explore the drain current behavior of the AOS TFTs for next-generation display circuit application.

An analytical surface-potential-based drain current model of dynamic-depletion (DD) polysilicon (poly-Si) thin-film transistors (TFTs) is proposed in this paper. In the 1-D Poisson equation, total charge density is reformulated by an effective charge density, which allows a closed-form surface potential calculation scheme. Different boundary conditions between partial depletion and full depletion are calculated and unified into one back-gate potential in the DD mode, which allows a unified-form surface potential calculation scheme. Combining with Gauss’s theory, we explicitly solve a closed- and unified-form surface potential of DD poly-Si TFTs. Based on the solution of the surface potential, the drain current is derived analytically from the Pao–Sah integration. Furthermore, our solution is verified by numerical results and experimental data, respectively. As a result, such a model can accurately predict I–V characteristics of DD poly-Si TFTs and provide computational efficiency for TFT process optimization and circuit simulations.

We propose an explicit surface-potential-based direct current (dc) model for fully depleted polysilicon (poly-Si) thin-film transistors (TFTs). Being analytical and explicit, the proposed model is a solid base for compact models of these devices. The essential for our model is the explicit calculation of the surface potential, using the Lambert W function. Subsequently, using the surface potential, we also develop the expressions for charge and current, employing well established approaches, which include integration of carrier’s charge for drain current. Furthermore, the solutions of surface potential and drain current were validated by numerical results and experimental data, respectively. Finally, we discussed in detail about the effects on the surface potential and dc properties from the full depleted poly-Si TFT parameters. As a result, such a model is suitable to be implemented into computer-aided simulations of both device and circuit designs, due to its high computational accuracy and efficiency.