New Concepts in All-Metal-Oxide-Based Ultraviolet Transparent Photovoltaics

The performance of photovoltaic systems is mostly determined by the materials used in their construction, regardless of the kind of application. We report on transparent broadband photodetectors based on p-Co
₃
O
₄
and a heterojunction of n-ZnO, n-TiO
₂
, or n-SnO
₂
that fits the needs of transparent optoelectronic devices. The heterojunction devices are fabricated by sputtering method. The energy band alignments are investigated with the aim of developing an efficient photodetector. The average transmittance values in the visible light range (400–800 nm) for TiO
₂
, ZnO, and SnO
₂
are observed to be approximately 80%, 74%, and 66%, respectively. The current–voltage characteristics of the devices are also investigated and non-Ohmic characteristics are observed. Furthermore, a photovoltage study with post-rapid thermal processing (RTP) is carried out. It is found that enhancing the carrier lifetime is an efficient way to improve the performance of the devices. With an increased minority carrier lifetime, the transient photovoltage of the RTP-treated TiO
₂
/Co
₃
O
₄
device shows slow decay.