Printed and flexible photovoltaics from aqueous solutions with integrated power electronics for energy harvesting

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

Abstract: Non-Technical This work aims to print flexible solar modules integrated with power electronics. Power electronics ensure that the maximum power is drawn from the solar module even if lighting conditions change. Printing electronics from solution is an additive process that could offer cost, energy and materials savings when compared to lithographic processes. For the power electronics, printed passive components'inductors, capacitors, and resistors will be integrated with silicon chips to ensure maximum performance in a flexible form factor. The intended solar modules will be printed from water-based inks eliminating the health and environment risks posed by typical organic solvents used in printed organic electronics. This project has the potential to take the necessary steps for the field of organic electronics, specifically organic photovoltaics, to evolve from single idealized devices to a low-cost mature technology. Emerging fields such as flexible and wearable electronics require a reliable manufacturing process for power supply and this work will impact flexible power harvesting systems and their integration with a load device. The proposed activities are addressing one of the biggest challenges of organic electronics: reliable manufacturing of flexible integrated devices for a specific application. Technical: In order to accomplish such a low-cost environmentally friendly energy harvesting system, this work will focus on three tasks. The first task is ink formulation for the components of the integrated power system. The aqueous inks for the active layer in the solar module will consist of nanoparticles fabricated using a mini-emulsion method. The work will characterize the variables in the fabrication process, using a combination of size, absorption, and electrical measurements to determine the compositions of materials that provide ideal morphology for photovoltaic performance. Polymers with different functional groups have been selected to determine how functional groups, which are known to affect a polymer's solubility and surface energy, also affect nanoparticle size and stability in water. Ink formulation will also take place for power electronic components, such as capacitors. The goal is to achieve high specific capacitance while maintaining fabrication reproducibility. The second task is to develop printing methods for polymer solar cells from aqueous inks and power electronic components. Blade coating and screen printing will be used for polymer solar cells and power electronics, respectively. Printed passive components will be developed, studied and characterized for maximum power point tracking, so that the solar cells may be operated efficiently in various irradiances. The third task is to integrate the organic solar cell modules with power electronics. Monolithically integrated solar modules will be designed and fabricated by printing series-connected solar cells, and the performance of the solar modules and maximum power point tracking circuit will be characterized under realistic practical conditions. The goal is to design a photovoltaic energy harvesting system that will perform at its maximum efficiency at both indoor and outdoor light intensities, with the intent of use with loads spanning a range of sensors, in addition to portable and wearable devices. In addition to these tasks, the project will utilize environmentally friendly methods to address the challenge presented by the use of organic solvents in a manufacturing process. For the outreach program it is planned to develop science modules for use with middle school students. The project will involve two REU programs, with one designed to involve community college students in the proposed research.