OPVs are distinguished by their thinness and flexibility. Most OPVs are a thousand times thinner than a normal silicon solar cell (Mellit & Benghanem, 2020).
OPVs can be produced on curved surfaces and flexible backings due to their thinness and flexibility. For instance, they can be incorporated into the fabric of tents, bags, and even garments.
Solar cells can now be deployed in a far wider range of places than only rooftops and solar farms thanks to OPV technology. OPV cells are perfectly suited to power mobile applications — camping gear, wearable technologies, or phone chargers (Naushad, Rajendran, & Al-Enizi, 2020).
Production of OPVs
Tang presented the first two-component OPV in 1986, but because of the dependency on bilayer cells, efficiencies remained low for several years (Forrest, 2020).
The bulk heterojunction (BHJ) cell was introduced in 1995 as a solution to this problem (Agugliaro & GarcĂa, 2020).
Instead of a conventional two-layer arrangement, the donor and acceptor components are closely combined at the nanoscale level, enabling adequate diffusion distance boundaries to be scattered across the active layer while retaining the thickness required for absorption.
Steps
- Light with high enough energy levels is absorbed by the OSC and excites electrons from the HOMO to the LUMO to form an exciton. If the energy of the light being absorbed is greater than the band gap, the electron will move to a higher level (Agugliaro & GarcĂa, 2020).
- The exciton diffuses via the OSC element to the donor-acceptor junction for exciton disintegration.
- The electron travels to the acceptor, while the hole remains at the donor. Such charge carriers are drawn together, resulting in a charge-transfer condition
- The charge-carriers diffuse across the necessary interfacial layers with holes to the anode or electrons to the cathode.
- The charge carriers are captured at the electrodes and flow through the external circuit, thus generating electricity.
OPV Current-Voltage Curve
The maximal photocurrent generation value is the short circuit current (Jsc) and it is the y-intercept value of a conventional current-voltage curve with current on the y-axis and voltage on the x-axis (Forrest, 2020).
If there is no current flowing through the OPV cell, the voltage is called the open-circuit voltage (Voc) and on a current-voltage curve, this correlates to the x-intercept.
This value is highly reliant on the active layer components HOMO and LUMO energy levels.
Because power is equal to the product of voltage and current, peak power happens when the product of voltage and current is maximized (Forrest, 2020).
References
Agugliaro, F. M., & GarcĂa, A. F. (2020). Surfaces and interfaces for renewable energy. MDPI.
Forrest, S. R. (2020). Organic electronics: foundations to applications. Oxford University Press.
Mellit, A., & Benghanem, M. (2020). A practical guide for advanced methods in solar photovoltaic systems. Springer Nature.
Naushad, M., Rajendran, S., & Al-Enizi, A. M. (2020). New technologies for electrochemical applications. CRC Press.