Transparent Photovoltaic (TPV) technologies represent a promising branch within photovoltaics, seeking to expand their applications by overcoming challenges related to on-site integration, especially within architectural elements related to BIPV, and more recently, also in the areas of IoT and Agrivoltaics. Unlike conventional approaches solely focused on efficiency, TPV introduces two additional dimensions: transparency and aesthetics, which pose added challenges to the device architecture. Moreover, for TPV technologies to be translated into competitive products it is critical to work on sustainable and stable materials that at least meet the stringent requirements for any PV technologies in conjunction with the transparency and aesthetic value that allow for seamless integration.

This challenge is being actively investigated using different materials, such as organic materials and perovskites. However, oxide-based structures constitute a very attractive prospect as they can be integrated as different functional layers in the solar cell architecture (i.e. as absorber, Charge Transport Layer and transparent electrical contacts). Additionally, many binary or ternary oxide compounds present high bandgap, tuneable conductivity, low deposition temperatures and can be deposited by a plethora of techniques that are possible to upscale for industrial purposes. Another key aspect is that many oxide materials are stable, cheap and CRM-free. Given these aspects the challenge is on how to combine them in advanced device architectures (with other oxides or materials) to develop a final device that is efficient, transparent and aesthetically pleasing that can be integrated in architectural components (windows, canopies, façades) or even on devices that present low power draws such as smartphones or screens and IoT devices and sensors.

Herein, we will discuss the basic principles of TPV as well as the state of the art of oxide-based strategies. This includes two main approaches that are based on either the development of Zn(O.S) UV-selective absorbers and on the optimisation of oxide-based architectures integrating nanometric a-Si:H layers. Main challenges and late results achieved in both strategies will be reviewed, including the achievement of record devices with Light Utilisation Efficiency up to 1.3%, transparency in the range between 30% and 70% and photoconversion efficiencies up to 5%.