Dear Abdul Sattar ,

The construction and design of thermoelectric nanogenerators (TENGs) can significantly influence their performance, including the power factor and open-circuit voltage. The main differences between uni-leg (p-type or n-type) and bi-leg (both p-type and n-type) TENGs lie in their working principles and the materials used for each leg.

Uni-leg TENGs:

Bi-leg TENGs:

Key Differences:

In summary, while uni-leg TENGs are simpler in design, bi-leg TENGs have the potential for higher performance by leveraging the complementary properties of both p-type and n-type thermoelectric materials. The choice between them depends on the specific requirements and constraints of your application. Experimental testing and optimization may be necessary to determine the most effective design for your thermoelectric nanogenerator.

Dear Len Leonid Mizrah ,

Thank you for your comprehensive answer to the question.

To add further to the question, what is your opinion on how the open-circuit voltage will evolve by using a bi-leg TENG configuration? Is there any mathematical expression for measuring the cumulative open-circuit voltage of the bi-leg TENGs?

For example, the following equation is typically used to calculate the open-circuit voltage for uni-leg TENGs:

Voc= ∆T x S x N

Here, 'Voc' is the open-circuit voltage, '∆T' is the temperature gradient, 'S' is the Seebeck Coefficient, and 'N' is the number of thermoelectric legs.

Dear Abdul Sattar ,

The open-circuit voltage (Voc) in a bi-leg Thermoelectric Nanogenerator (TENG) configuration can be affected by various factors, and there isn't a universal mathematical expression that covers all possible scenarios. However, I can provide some insights and considerations for a bi-leg TENG.

In a bi-leg TENG configuration, two thermoelectric legs are often used to enhance the voltage output. The open-circuit voltage (Voc) in this case can be influenced by the temperature difference (∆T), Seebeck coefficient (S), and the number of thermoelectric legs (N), similar to the uni-leg TENG configuration. However, the specific relationship may be more complex due to interactions between the two legs.

To provide a more accurate expression, you might need to consider additional factors such as the thermal and electrical conductivity of the materials used, the thermal interface resistance between the legs, and any other relevant parameters specific to your bi-leg TENG setup.

A generalized expression for the open-circuit voltage in a bi-leg TENG configuration might look like this:

Voc=(ΔT//Reff)⋅(S1+S2)⋅N

Here, S1​ and S2​ are the Seebeck coefficients of the two legs, and Reff​ is the effective thermal resistance, which takes into account the thermal interface resistance between the legs.

It's important to note that deriving a specific expression would require a detailed understanding of the materials, geometry, and operating conditions of your bi-leg TENG. You may need to perform experiments or simulations to determine the actual parameters and their impact on the open-circuit voltage.

Consulting relevant literature in the field and collaborating with experts in thermoelectric energy harvesting could provide further guidance on developing a comprehensive model for your specific bi-leg TENG configuration.