Inexpensive, Earth-Abundant, and Tunable Hole Transport Material for CdTe Solar Cells


Project ID:  D2017-08



Photovoltaic (PV) cells have been produced with a wide variety of materials for each functional layer. The typical PV is a substrate layer coated with a semiconductor layer and two ohmic contacts. Thin film solar cells use a thin absorbing layer, such as Cadmium telluride (CdTe). CdTe is the most eco-friendly, high efficiency, low cost PV, with the shortest energy payback time. Development of a stable and efficient back contact determines the long-term stability of the solar cells. Back contacts are typically made of materials containing copper, gold, zinc, aluminum, etc. These materials adversely react with the semi-conductive layers and cause a Schottky junction to form, preventing photo-generated holes from reaching the back contact metal. Therefore, the back contact often reduces performance of the solar cell. Current projects seek higher cell efficiencies and can be accomplished through minimizing or eliminating back barrier effects.


Invention Description

The researchers at University of Toledo have addressed the need for a suitable hole transport layer (HTL) in CdTe solar cells to improve the back barrier effects. The interface layer technology uses an organo metallic halide perovskite as a HTL. Deposition methods create regions rich in Te. The perovskite class of materials is tunable based on variations in the halide anion, cation, and metal and related dopant atoms. This novel feature allows for improvements over traditional Cu/Au in CdTe solar cell, such as increasing the open circuit voltage by and fill factor.



•       Hole transport layer (HTL) as the back contact to CdS/CdTe solar cells.



•       Increased cell performance (efficiency and fill factor)

•       Tunable band gap to obtain specific properties

•       Film is inexpensive and easy to process

•       Longer carrier life time

•       High absorption coefficient and charge carrier motility, low excitation binding energy

•       Negligible hystersesis, recombination loss, and crossover

•       Is compatible with semiconductor layers such as CdTe, CIGS, CZS, CZTSSe

IP Status:       Patent Pending, 2018/0219166 A1


Patent Information:
For Information, Contact:
Katherine Pollard
Licensing Associate
The University of Toledo
Randall Ellingson
Khagendra Bhandari
Michael Heben
Suneth Watthage
Hole transport layer
Solar cell