Design of high efficiency solar cells by photoluminescence studies

Abstract

A metal-organic chemical vapor deposition (MOCVD) AI,Gal -,As passivated GaAs single junction solar cell with AM1.5 efficiency of 24.8% was recently reported. Growth process research was greatly expedited by complementary time-resolved photoluminescence measurements on double heterostructures. The latter simulated the active regions of the solar cell and produced values of the minority carrier lifetime and interface recombination velocity of the components of the solar cell. Photon recycling was shown to be a significant process in the effective lifetime of the various structures.Interface recombination was found to limit the lifetime in materials grown at temperatures below 740°C.

Fourier transform-luminescence spectroscopy of semiconductor thin films and devices

“…Background solution (BS) treatment of CIGS films consisted of carrying out the CBD process without thiourea. A "BS + thiourea" treatment consisting of the BS procedure followed by a deionized water rinse, and a repetition of the CBD process without CdSO 4 , was applied to other CIGS samples. The BS and BS + thiourea treatments left no continuous film of CdS on the CIGS surfaces.…”

“…For example, NIR PL spectroscopy has been used to detect light-or heat-induced defects ("dangling bonds") in hydrogenated amorphous silicon [1] and has been correlated with the efficiency of PV devices produced from copper indium diselenide (CuInSe 2 , or CIS) thin films [2]. Time-resolved (TR) NIR PL spectroscopy has been used to measure the minority carrier lifetimes τ in Al x Ga 1-x As [3] and to optimize the design of highefficiency, AlGaAs-passivated GaAs solar cells [4]. Although some of this work has been done at room temperature, detection of weak NIR PL emission beyond the wavelength range of Si and photomultiplier detectors when using dispersive spectrophotometers has typically required cryogenic cooling of semiconductor samples [1,2].…”

New III-V cell design approaches for very high efficiency. Annual subcontract report, 1 August 1991--31 July 1992

“…To separate interface and bulk recombination, the decay constants of several DH's with identical electron densities but varying thicknesses are measured, and a plot of ~/TDH vs. 2/w is constructed [18,33]. According to Eq.…”

Recombination lifetime and performance of III-V compound photovoltaic devices

“…Recent studies [41,42] found that the recombination velocity at the MOCVD n-Al0,,Ga0~,,As/GaAs interface changed by orders of magnitude, depending on growth temperature. Diagnostic DH devices were made in paralled with PV devices hoping to improve the PV efficiency by optimizing the growth temperature.…”